Imidazo[2,1-f][1,2,4]triazin-4-amine derivatives used as tlr8 agonists

ABSTRACT

Disclosed are an imidazo[2,1-f][1,2,4]triazin-4-amine derivative used as a TLR8 agonist or a stereoisomer thereof or a pharmaceutically acceptable salt thereof, and a pharmaceutical composition containing same. Further disclosed is a method for treating cancers using the imidazo[2,1-f][1,2,4]triazin-4-amine derivative or the stereoisomer thereof or the pharmaceutically acceptable salt thereof as a TLR8 agonist.

The invention discloses an imidazo[2,1-f][1,2,4]triazin-4-aminederivative used as a TLR8 agonist or a stereoisomer thereof or apharmaceutically acceptable salt thereof, and a pharmaceuticalcomposition comprising the same. The invention further discloses amethod for treating cancers by using theimidazo[2,1-f][1,2,4]triazin-4-amine derivative or the stereoisomerthereof or the pharmaceutically acceptable salt thereof as a TLR8agonist.

BACKGROUND OF THE INVENTION

Toll-like receptors (TLRs), which belong to the family of patternrecognition receptors (PRRs), play a key role in early innate immuneresponse by sensing highly conserved pathogen associated molecularpatterns (PAMPs) and endogenous damage-associated molecular patterns(DAMPs) (Barton, G. M. and R. Medzhitov (2002). “Toll-like receptors andtheir ligands.” Curr Top Microbiol Immunol 270: 81-92).

Ten different TLRs have been identified in humans. Among them. TLR7,TLR8 and TLR9 belong to the same subfamily of TLR based on their genomestructure, sequence similarity and endosome localization. They have alimited expression pattern, and only expressed in some types of immunecells. TLR7 is expressed in B cells and plasma cell-like dendritic cells(pDCs); and TLR8 is expressed in monocytes and myeloid dendritic cells(mDCs) (Iwasaki, A. and R. Medzhitov (2004). “Toll-like receptor controlof the adaptive immune responses.” Nat Immunol 5(10): 987-995).

In addition to natural ligand single-stranded RNA, imidazoquinolone (or“imiquimod-like” ligand) and guanosine analogues also activate TLR7and/or TLR8 with different specificity. The activation of TLR7 and/orTLR8 triggers the maturation of dendritic cells (DCs) and the secretionof pro-inflammatory cytokines (van Duin, D., et al. (2006). “TriggeringTLR signaling in vaccination.” Trends Immunol 27(1): 49-55). CTL and NKcells are further activated and proliferated by DC stimulated bycytokines and antigen presentation. Therefore, the characteristics ofTLR agonists constitute an effective strategy to enhance the anti-cancerimmunity (Adams, S. (2009). “Toll-like receptor agonists in cancertherapy.” Immunotherapy 1(6): 949-964).

Imiquimod (TLR7 agonist), as a single antitumor agent withimmuno-stimulating ability, has been successfully used in the treatmentof many primary skin tumors and skin metastases (Stary, G., et al.(2007). “Tumoricidal activity of TLR7/8-activated inflammatory dendriticcells.” J Exp Med 204(6): 1441-1451., Aranda. F., et al. (2014). “TrialWatch: Toll-like receptor agonists in oncological indications.”Oncoimmunology 3: e29179).

WO2016023511 discloses that pyrrolopyrimidine compounds as a TLR7agonist is used for preparing antiviral drugs.

Motolimod (VTX-2337) is a small molecule agonist specific for TLR8,which is used as an immunotherapy for various cancer types in clinicaldevelopment. Motolimod, when used as an immunotherapy for cancerpatients, has good safety, showing limited toxicity and no evidence ofcytokine storms (Ann Oncol. 2017; 28: 996-1004). However, its benefitsare usually limited to the subjects with injection site response (ClinCancer Res. Jan. 1, 2018: 24 (1): 62-72. Ann Oncol. May 1, 2017; 28(5):996-1004).

At present, a great deal of efforts have been devoted to the preclinicaland clinical development of TLR agonists for cancer treatment.Therefore, it is necessary to develop more effective TLR agonists forcancer treatment.

SUMMARY OF THE INVENTION

Unexpectedly and surprisingly, the inventors found thatimidazo[2,1-f][1,2,4]triazin-4-amine derivatives disclosed in theinvention show more effective activity as TLR8 agonists, especially whenring A in formula (I) is a non-aromatic ring.

In first aspect, the invention discloses a compound of formula (I),

or a pharmaceutically acceptable salt thereof, or a stereoisomerthereof, wherein:

X is N or CR⁷:

wherein R⁷ is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl:

L¹ is —(CR^(a)R^(b))_(m)—, —O—, —S—, —S(O)—, —SO₂—, —C(O)—, —C(O)O—,—OC(O)—, —NR^(a)—, —C(O)NR^(a)—, —NR^(a)C(O)—, —NR^(a)C(O)O—,—NR^(a)C(O)NR^(b)—, —SO₂NR^(a)—, —NR^(a)SO₂—, —NR^(a)S(O)₂NR^(b)—,—NR^(a)S(O)NR^(b)—, —C(O)NR^(a)SO₂—, —C(O)NR^(a)SO—, or—C(═NR^(a))NR^(b)—,

wherein m is 0 to 8, and one or two CR^(a)R^(b) moieties in—(CR^(a)R^(b))_(m)— are not replaced or replaced by one or more moietiesselected from O, S, SO, SO₂, C(O) and NR^(a);

R^(a) and R^(b) in each occurrence are independently hydrogen, halogen,alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl, heteroaryl or —OR^(c);

wherein R^(c) is hydrogen, alkyl, alkoxy-alkyl-, alkenyl, alkynyl,cycloalkyl, aryl, heterocyclyl or heteroaryl;

R¹ is —OR^(1a), —SR^(1a), —NR^(1a)R^(1b), —COR^(1a), —SO₂R^(1a),—C(═O)OR^(1a), —C(═O)NR^(1a)R^(1b), —C(═NR^(1a))NR^(1b)R^(1c),—N(R^(1a))C(═O)R^(1b), —N(R^(1a))C(═O)OR^(1b),—N(R^(1a))C(O)NR^(1b)R^(1c), —N(R^(1a))S(O)NR^(1b)R^(1c),—N(R^(1a))S(O)₂NR^(1b)R^(1c), —NR^(1a)SO₂R^(1b), alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl, orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachindependently and optionally substituted with one or two or threesubstituents R^(1d);

R^(1a), R^(1b) and R^(1c) are independently hydrogen, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachoptionally substituted with one or two or three substituents selectedfrom: halogen, —C₁₋₈ alkyl optionally substituted with R^(1c),cycloalkyl optionally substituted with R^(1e), heterocyclyl optionallysubstituted with R^(1c), aryl optionally substituted with R^(1c),heteroaryl optionally substituted with R^(1c), CH₃—(OCH₂CH₂)_(n)— (wheren is 3 to 10) or —OR^(1f):

wherein R^(1e) is halogen, nitro, cyano, hydroxyl, amino (—NH₂),alkylamino, dialkylamino. —C₁₋₆ alkyl optionally substituted withhalogen, carboxyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl,dialkylaminocarbonyl;

wherein R^(1f) is alkyl, cycloalkyl, heterocyclyl, aryl or heteroaryl,each being optionally substituted with —C₁₋₄alkyl or halogen;

each R^(1d) in each occurrence is independently hydrogen, oxo, —CN,—NO₂, hydroxyl, amino (—NH₂), alkylamino, dialkylamino, halogen,haloalkyl, alkyl, haloalkoxy, alkoxy, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl:

R² and R³ in each occurrence are independently hydrogen, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl isoptionally substituted with 1-3 substituents selected from: oxo, —CN,—NO₂, amino (—NH₂), alkylamino, dialkylamino, halogen, hydroxyl,haloalkyl, alkyl, haloalkoxy, alkoxy, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl;

R⁴ is hydrogen, halogen, cyano, —NO₂, —OR^(4a), —SR^(4a),—NR^(4a)R^(4b), —COR^(4a), —SO₂R^(4a), —C(═O)OR^(4a),—C(═O)NR^(4a)R^(4b), —C(═NR^(4a))NR^(4b)R^(4c), —N(R^(4a))C(═O)R^(4b),—N(R^(4a))C(═O)OR^(4b), —N(R^(4a))C(O)NR^(4b)R^(4c),—N(R^(4a))S(O)NR^(4b)R^(4c), —N(R^(4a))S(O)₂NR^(4b)R^(4c),—NR^(4a)SO₂R^(4b), alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl, or heteroaryl, wherein the alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl are each independently and optionally substitutedwith one or two or three substituents R^(4d);

R^(4a), R^(4b) and R^(4c) are independently hydrogen, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, any orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachoptionally substituted with halogen, hydroxyl, NH₂—, alkylamino,dialkylamino or alkoxy;

each R^(4d) in each occurrence is independently hydrogen, oxo, —CN,—NO₂, halogen, hydroxyl, NH₂—, alkylamino, dialkylamino, alkyl, alkoxy,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl, wherein the alkyl, alkoxy, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroarylare each optionally substituted with halogen, hydroxyl, NH₂—,alkylamino, dialkylamino or alkoxy;

ring A is a cycloalkyl or heterocyclyl ring;

R⁵ is halogen, oxo, hydroxyl, alkyl, haloalkyl, alkoxy, haloalkoxy or—C(═O)OR^(5a), wherein R^(5a) is hydrogen, alkyl or haloalkyl:

p is 0, 1, 2 or 3:

L² is a direct bond, —(CR^(f)R^(g))—, —O—, —S—, —S(O)—, —SO₂—, —C(O)—,—C(O)O—, —OC(O)—, or —NR^(d)— where R^(d) is —C₁₋₆ alkyl, wherein t is 1to 8, and one or two CR^(f)R^(g) moieties in —(CR^(f)R^(g))_(t)— are notreplaced or replaced by one or more moieties selected from O, S, SO,SO₂, C(O) and NR^(f);

R^(f) and R^(g) in each occurrence are independently hydrogen, alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl;

R⁶ is hydrogen, —NR^(6a)R^(6b), alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl, whereinthe alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl or heteroaryl are each independently and optionallysubstituted with one or two or three substituents R^(6c);

R^(6a) and R^(6b) are independently hydrogen, alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachoptionally substituted with halogen, hydroxyl, NH₂—, alkylamino,dialkylamino or alkoxy;

R^(6c) is independently hydrogen, halogen, cyano, —NO₂, —OR^(6d),—SR^(6d), —NR^(6d)R^(6e), —COR^(6d), —SO₂R^(6d), —C(═O)OR^(6d),—C(═O)NR^(6d)R^(6e), —C(═NR^(6d))NR^(6e)R^(6f), —N(R^(6d))C(═O)R^(6e),—N(R^(6d))C(═O)OR^(6e). —N(R^(6d))C(O)NR^(6e)R^(6f),—N(R^(6d))S(O)NR^(6e)R^(6f), —N(R^(6d))S(O)₂NR^(6e)R^(6f).—NR^(6d)SO₂R^(6e), alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl or heteroaryl, wherein the alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl are each independently and optionally substitutedwith one or two or three substituents R^(6g).

R^(6d), R^(6e) and R^(6f) are independently hydrogen, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachoptionally substituted with one or two or three substituents R^(6g);

each R^(6g) in each occurrence is independently hydrogen, halogen,cyano, —NO₂, —OR^(6h), —SR^(6h), —NR^(6h)R^(6i), —COR^(6h), —SO₂R^(6h),—C(═O)OR^(6h), —C(═O)NR^(6h)R^(6i), —C(═NR^(6h))NR^(6i)R^(6j),—N(R^(6h))C(═O)R^(6i), —N(R^(6h))C(═O)OR^(6i),—N(R^(6h))C(O)NR^(6i)R^(6j), —N(R^(6h))S(O)NR^(6i)R^(6j),—N(R^(6h))S(O)₂NR^(6i)R^(6h), —NR^(6h)SO₂R^(6i), alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl; and

R^(6h), R^(6i) and R^(6j) are independently hydrogen, alkyl, alkoxy,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl, wherein the alkyl, alkoxy, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroarylare each independently and optionally substituted with one or two orthree substituents selected from: halogen, —C₁₋₄ alkyl, —C₁₋₄ alkoxy,hydroxyl, nitro, —NH₂, alkylamino, dialkylamino or cyano.

Definition of X

In some embodiments, X is N. In some embodiments, X is CR⁷, wherein R⁷is as defined for formula (I). In some embodiments, X is CH.

Definition of L¹

In some embodiments, m is 0 to 5, or 1 to 3, or 1.

In some embodiments, L¹ is —CR^(a)R^(b)—, —O—, —S—, —S(O)—, —SO₂— or—C(O)—, wherein R^(a) and R^(b) in each occurrence are independentlyhydrogen, halogen, —C₁₋₈ alkyl or —OR^(c), wherein R^(c) is hydrogen or—C₁₋₄ alkyl. In other embodiments, L¹ is —CR^(a)R^(b)—, wherein R^(a)and R^(b) in each occurrence are independently hydrogen, halogen. —C₁₋₈alkyl (preferably —C₁₋₄alkyl, and more preferably methyl) or —OH. Insome embodiments, L¹ is —CH₂—, —CH(OH)— or —CH(CH₃)—. In someembodiments, L¹ is —CH₂—.

Definition of R¹

In some embodiments, R¹ is —OR^(1a) or —NR^(1a)R^(1b), wherein R^(1a)and R^(1b) are as defined for formula (I).

In some embodiments, R¹ is —OR^(1a) or —NR^(1a)R^(1b), wherein R^(1a)and R^(1b) are independently hydrogen. —C₁₋₈ alkyl or —C₂₋₈ alkenyl, andthe —C₁₋₈ alkyl or —C₂₋₈ alkenyl are each optionally substituted withone or two or three substituents selected from, heterocyclyl optionallysubstituted with R^(1e), aryl optionally substituted with R^(1e),CH₃—(OCH₂CH₂)_(n)— (where n is 3 to 10, preferably 4-8, and morepreferably 5-7), or —OR^(1f).

wherein R^(1e) is halogen, —C₁₋₆ alkyl optionally substituted withhalogen, carboxyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl,dialkylaminocarbonyl;

wherein R^(1f) is —C₁₋₈ alkyl, aryl or heteroaryl, each of which isoptionally substituted with —C₁₋₄ alkyl or halogen.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is hydrogen.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyloptionally substituted with one or two or three substituents selectedfrom: halogen, —C₁₋₈ alkyl optionally substituted with R^(1e),cycloalkyl optionally substituted with R^(1e), heterocyclyl optionallysubstituted with R^(1e), aryl optionally substituted with R^(1e),heteroaryl optionally substituted with R^(1e), CH₃—(OCH₂CH₂)_(n)— (wheren is 3 to 10), or —OR^(1f), wherein R^(1e) and R^(1f) are as defined forformula (I).

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is substituted C₁₋₈alkyl. In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is linear. Insome embodiments, R¹ is —OR^(1a), wherein R^(1a) is branched alkyl. Insome embodiments, R¹ is —OR^(1a), wherein R^(1a) is branched alkyl,preferably —C₄₋₈ alkyl, wherein the branched substituent is at the αposition relative to the oxygen atom, including but not limited tobut-2-yl, pent-2-yl, pent-3-yl, hept-2-yl, hept-3-yl, hept-4-yl,oct-2-yl, oct-3-yl, oct-4-yl, or oct-5-yl. In some embodiments, R¹ ismethoxy, ethoxy, propoxy, butoxy, pentoxy, hexyloxy, heptyloxy oroctoxy. In some embodiments, R¹ is preferably propoxy, isopropoxy,n-butoxy, isobutoxy, but-2-yloxy (sec-butoxy), pent-2-yloxy,pent-3-yloxy, 2-methylbutoxy, hep-2-yloxy, hep-3-yloxy, hep-4-yloxy,oct-2-yloxy, oct-3-yloxy, oct-4-yloxy, or oct-5-yloxy. In someembodiments, R¹ is n-butoxy, but-2-yloxy (sec-butoxy), pent-2-yloxy,pent-3-yloxy, hept-2-yloxy, hept-3-yloxy, hept-4-yloxy, oct-2-yloxy,oct-3-yloxy, oct-4-yloxy, or oct-5-yloxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₄ alkyl,preferably —C₄₋₅ alkyl, wherein the alkyl is substituted with 1-3halogens, such as fluorine.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl,preferably —C₁₋₃ alkyl, wherein the alkyl is substituted with cycloalkyloptionally substituted with R^(1e), heterocyclyl optionally substitutedwith R^(1e), aryl optionally substituted with R^(1e) or heteroaryloptionally substituted with R^(1e), wherein R^(1e) is as defined forformula (I).

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl,preferably —C₁₋₃ alkyl, wherein the alkyl is substituted withheteroaryl, such as 5-6 membered heteroaryl comprising one or two orthree heteroatoms selected from oxygen, nitrogen or optionally oxidizedsulfur as ring members, wherein the heteroaryl is optionally substitutedwith —C₁₋₆ alkyl, preferably —C₁₋₄ alkyl, and more preferably methyl. Insome embodiments, heteroaryl is pyridinyl or imidazolyl or isoxazolyl.In some embodiments, R¹ is pyridin-3-ylmethoxy,2-(1H-imidazol-1-yl)ethoxy or (5-methylisoxazol-3-yl)methoxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl, andpreferably —C₁₋₃ alkyl, wherein the alkyl is substituted with aryl suchas phenyl. In some embodiments, R¹ is 2-phenylethoxy or 3-phenylpropoxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl,preferably —C₁₋₃ alkyl, wherein the alkyl is substituted with —OR^(1f),wherein R^(1f) is —C₁₋₈ alkyl or aryl (e.g., phenyl). In someembodiments, R¹ is 2-methoxyethoxy or 2-phenoxyethoxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl, andpreferably —C₁₋₃ alkyl, wherein the alkyl is substituted withCH₃—(OCH₂CH₂)_(n)—, wherein n is 3 to 10, preferably 3 or 4 or 5. Insome embodiments, R¹ is 2,5,8,11-tetraoxatridecan-13-yloxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₂₋₈ alkenyl;preferably —C₂₋₆ alkenyl; and most preferably —C₄₋₆ alkenyl. In oneexample, R¹ is but-3-enyloxy.

In some embodiments, R¹ is —NR^(1a)R^(1b), wherein R^(1a) and R^(1b) areeach hydrogen or —C₁₋₈ alkyl, and preferably —C₁₋₆ alkyl, wherein thealkyl is optionally substituted with one or two or three substituentsselected from: halogen, —C₁₋₈ alkyl optionally substituted with R^(1e),cycloalkyl optionally substituted with R^(1e), heterocyclyl optionallysubstituted with R^(1e), aryl optionally substituted with R^(1e) orheteroaryl optionally substituted with R^(1e), wherein R^(1e) is —C₁₋₆alkyl, such as methyl.

In some embodiments, R¹ is —NR^(1a)R^(1b), wherein R^(1a) is hydrogen,and R^(1b) is linear or branched —C₁₋₈ alkyl. In some embodiments, R¹ is—NR^(1a)R^(1b), wherein R^(1a) is hydrogen, R^(1b) is branched alkyl,and preferably-C₄₋₈ alkyl, wherein the branched substituent is at the αposition relative to the oxygen atom, including but not limited tobut-2-yl, pent-2-yl, pent-3-yl, hept-2-yl, hept-3-yl, hept-4-yl,oct-2-yl, oct-3-yl, oct-4-yl, or oct-5-yl.

In some embodiments, R¹ is butylamino, N-butyl-N-methylamino orisopentylamino.

In some embodiments, R¹ is optionally partially or completelydeuterated, that is, one or more carbon-bonded hydrogen atoms in thedefinition of R¹ are replaced by one or more deuterium atoms.

Definition of R² and R³

In some embodiments, R² and R³ in each occurrence are independentlyhydrogen or C₁₋₈ alkyl, and preferably C₁₋₆ alkyl. In some embodiments,R² and R³ are both hydrogen.

Definition of R⁴

In some embodiments, R⁴ is hydrogen.

Definition of R⁵

In some embodiments, R⁵ is halogen, oxo, hydroxyl, C₁₋₈ alkyl,halogenated C₁₋₈ alkyl, C₁₋₈ alkoxy, halogenated C₁₋₈ alkoxy, or—C(═O)OR^(5a), wherein R^(5a) is hydrogen. C₁₋₈ alkyl, or halogenatedC₁₋₈ alkyl; and p is 0, 1, or 2.

In some embodiments, R⁵ is halogen, oxo, C₁₋₃ alkyl, halogenated C₁₋₃alkyl, C₁₋₃ alkoxy, or halogenated C₁₋₈ alkoxy. In some embodiments, R⁵is methyl, ethyl, propyl, methoxy, ethoxy, propoxy, isopropoxy,trifluoromethoxy or trifluoromethyl. In some embodiments, R⁵ is methyl.

In some embodiments, p is 1.

In some embodiments, R⁵ and L²-R⁵ are on ortho-positions of ring A.

Definition of Ring A

In some embodiments, ring A is heterocyclyl.

In some embodiments, ring A is 4-, 5-, 6-, 7-, 8- or 9-memberedmonocyclic heterocyclyl, which comprises one or two or three heteroatomsselected from oxygen, nitrogen or optionally oxidized sulfur as ringmembers, preferably 5- or 6-membered heteroaryl comprising one or twonitrogen atoms as ring members; and more preferably, 5- or 6-memberedheteroaryl comprising one nitrogen atom as a ring member. In someembodiments, ring A is azetidinyl (e.g., azetidin-1-yl, azetidin-2-yl,azetidin-3-yl, azetidin-4-yl), pyrrolidinyl (e.g., pyrrolidin-1-yl,pyrrolidin-2-yl, pyrrolidin-3-yl), piperidinyl (e.g., piperidin-1-yl,piperidin-2-yl, piperidin-3-yl, piperidin-4-yl), or azepanyl (e.g.,azepan-1-yl, azepan-2-yl, azepan-3-yl, azepan-4-yl): and preferablypiperidinyl (e.g., piperidin-1-yl, piperidin-4-yl). In some embodiments,ring A is piperazinyl (e.g., piperazin-1-yl or piperazin-2-yl).

In some embodiments, the heterocyclyl ring may comprise one or moredouble bonds (C═C or C═N), but it is not aromatic. However, theheterocyclyl ring is preferably saturated.

In some embodiments, ring A is spiro heterocyclyl or bridgedheterocyclyl, such as 5-20-membered, preferably 6-14-membered, and morepreferably 7-12-membered heterocyclyl. In some embodiments, theheterocyclyl is 7-azaspiro[3.5]nonyl, 3-azaspiro[3.1.0]hexyl,2-azaspiro[3.3]heptyl, 7-azaspiro[3.5]nonyl, 2-azaspiro[3.5]nonyl,2-azabicyclo[2.2.1]heptyl, 8-azabicyclo[3.2.1]octyl or2-azabicyclo[4.1.0]heptyl. More specifically, spiro heterocyclyl is7-azaspiro[3.5]non-2-yl, 3-azabicyclo[3.1.0]hex-6-yl,2-azaspiro[3.3]hept-6-yl, 7-azaspiro[3.5]non-2-yl,2-azaspiro[3.5]non-7-yl, 2-azabicyclo[2.2.1]hept-5-yl,8-azabicyclo[3.2.1]oct-3-yl or 2-azabicyclo[4.1.0]hept-5-yl.

In some embodiments, ring A is a cycloalkyl ring, such as 3-8-memberedmonocyclic cycloalkyl or 6-12-membered bicyclic cycloalkyl selected fromspiro-cycloalkyl, fused cycloalkyl or bridged cycloalkyl, such asbicyclo[1.1.1]pentyl (e.g., bicyclo[1.1.1]pent-1-yl). In someembodiments, ring A is cycloalkenyl or cycloalkynyl.

Definition of L²-R⁶

In some embodiments, L² is a direct bond, —(CH₂)_(t)—, —O—, —S—, —S(O)—,—SO₂—, —C(O)—, —C(O)O—, —OC(O)—, or —NR^(d)— where R^(d) is-C it alkyl,wherein t is 1 to 8, preferably 1 to 5, and more preferably 1 or 2 or 3:and R^(d) is —C₁₋₆ alkyl.

In some embodiments, L² is a bond, —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —O—, or—NR^(d)—, wherein R^(d) is —C₁₋₆ alkyl, preferably —C₁₋₄ alkyl, and morepreferably methyl.

In some embodiments, R⁶ is hydrogen, —NR^(6a)R^(6b), —C₁₋₈ alkyl, —C₂₋₈alkenyl, —C₂₋₈ alkynyl, -cycloalkyl, heterocyclyl, aryl or heteroaryl,wherein the —C₁₋₈ alkyl, —C₂₋₈ alkenyl, —C₂₋₈ alkynyl, -cycloalkyl,heterocyclyl, aryl or heteroaryl are each independently and optionallysubstituted with one or two or three substituents R¹:

R^(6a) and R^(6b) are independently hydrogen or —C₁₋₈ alkyl:

R^(6c) is independently hydrogen, halogen, —OR^(6d), —SR^(6d),—NR^(6d)R^(6e), —COR^(6d), —SO₂R^(6d), —C(═O)NR^(6d)R^(6e) or —C₁₋₈alkyl, wherein the —C₁₋₈ alkyl is independently and optionallysubstituted with one or two or three substituents R⁶⁸;

R^(6d) and R^(6e) are independently hydrogen, —C₁₋₈ alkyl, —C₂₋₈alkenyl, heterocyclyl or aryl, wherein the —C₁₋₈ alkyl, —C₂₋₈ alkenyl,heterocyclyl or aryl is each optionally substituted with one or two orthree substituents R^(6g);

R^(6g) in each occurrence is independently hydrogen, halogen, —OR^(6h),—SR^(6h), —NR^(6h)R^(6i), —N(R^(6h))C(═O)OR^(6i), —C₁₋₈ alkyl,heterocyclyl, aryl or heteroaryl, wherein R^(6h) and R^(6i) areindependently hydrogen or —C₁₋₈ alkyl.

Definition of L²-R⁶, Wherein L² is —(CR^(f)R^(g))_(t)— and R⁶ isHeterocyclyl

In some embodiments, L² is —(CR^(f)R^(g))_(t)— (where t, R^(f) and R^(g)are as defined for formula (I)), preferably —CH₂— or —CH₂CH₂—, and R⁶ isheterocyclyl optionally substituted with one or two substituents R^(6c),wherein R^(6c) is as defined for formula (I).

In some embodiments, the heterocyclyl as R⁶ is monocyclic. In someembodiments, the heterocyclyl is bicyclic. In some embodiments, theheterocyclyl is saturated. In some embodiments, the heterocyclyl is a5-8-membered saturated monocyclic ring which comprises one, two or threeheteroatoms selected from oxygen, nitrogen or optionally oxidized sulfuras ring members. In some embodiments, the heterocyclyl is a 5-, 6-, 7-or 8-membered saturated monocyclic ring comprising one or two or threenitrogen heteroatoms as ring members.

In some embodiments, the heterocyclyl as R⁶ is pyrrolidinyl (e.g.,pyrrolidin-1-yl, pyrrolidin-2-yl, pyrrolidin-3-yl), piperidinyl (e.g.,piperidin-1-yl, piperidin-2-yl, piperidin-3-yl, piperidin-4-yl,piperidin-5-yl), triazolyl (e.g., 1H-1,2,4-triazol-1-yl), azepanyl(e.g., azepan-2-yl, azepan-3-yl, azepan-4-yl, azepan-5-yl), piperazinyl(e.g., piperazin-1-yl, piperazin-2-yl, piperazin-3-yl) or morpholino. Insome embodiments, the heterocyclyl is bicyclic and comprises one, two orthree heteroatoms selected from oxygen, nitrogen or optionally oxidizedsulfur as ring members. In some examples, the heterocyclyl is(1S,4S)-2,5-diazabicyclo[2.2.1]hept-2-yl. In the above embodiments, theheterocyclyl as R⁶ is further optionally substituted with one or twosubstituents R^(6c). In some embodiments, R^(6c) is —NR^(6d)R^(6e),—COR^(6d), —OR^(6d) or —C₁₋₈ alkyl optionally substituted with hydroxyl,wherein R^(6d) and R^(6e) are independently hydrogen or —C₁₋₈ alkyl(preferably —C₁₋₃ alkyl) or phenyl, wherein the alkyl is optionallysubstituted with NH₂—, alkylamino or dialkylamino. In some embodiments,R^(6e) is amino, dimethylamino, 2-(dimethylamino)acetyl, methyl,3-hydroxypropyl or phenoxy. In some embodiments, L² is —CH₂— or—CH₂CH₂—. In some embodiments, R⁶ is pyrrolidin-1-yl, morpholino,piperidin-1-yl, 4-methylpiperazin-1-yl, piperazin-1-yl, piperidin-4-yl,4-(2-(dimethylamino)acetyl)piperazin-1-yl,(1S,4S)-2,5-diazabicyclo[2.2.1]hept-2-yl, 4-aminopiperidin-1-yl,3-(dimethylamino)pyrrolidin-1-yl, 4-phenoxypiperidin-1-yl,1H-1,2,4-triazol-1-yl, 4-(3-hydroxypropyl)piperazin-1-yl orpiperidin-3-yl.

Definition of L²-R⁶, Wherein L² is —(CR^(f)R^(g))— and R⁶ is—NR^(6a)R^(6b)

In some embodiments, L² is —(CR^(f)R^(g))_(t)— (where t, R^(f) and R^(g)are as defined for formula (I)), preferably —CH₂— or —CH₂CH₂—, and R⁶ is—NR^(6a)R^(6b), wherein R^(6a) and R^(6b) are as defined for formula(I). In some embodiments, L²- is —(CH₂)_(t)— (where t is 1 to 8,preferably 1 to 5, and more preferably 1 or 2 or 3), preferably —CH₂— or—CH₂CH₂—, and R⁶ is —NR^(6a)R^(6b), wherein R^(6a) and R^(6b) areindependently hydrogen or C₁₋₈ alkyl, and preferably C₁₋₆ alkyl. In someembodiments, L²-R⁶ are aminomethyl.

Definition of L²-R⁶, Wherein L² is a Bond and R⁶ is Alkyl, Alkenyl orAlkynyl

In some embodiments, L² is a bond and R⁶ is —C₁₋₈ alkyl, —C₂₋₈ alkenyl,or —C₂₋₈ alkynyl.

Definition of L²-R⁶, Wherein L² is —O— or —NR^(d-) and R⁶ is Alkyl,Alkenyl, Alkynyl, Heterocyclyl, Aryl or Heteroaryl

In some embodiments, L² is —O—, and R⁶ is —C₁₋₈ alkyl or heterocyclyl,wherein the —C₁₋₈ alkyl and heterocyclyl are optionally substituted withone or two R^(6c). In some embodiments, R^(6c) is —C₁₋₈ alkyl,—NR^(6d)R^(6e) and —COR^(6d), wherein R^(6d) and R^(6e) areindependently —C₁₋₈ alkyl (preferably —C₁₋₃ alkyl) optionallysubstituted with NH₂—, alkylamino or dialkylamino.

In some embodiments, L² is —NR^(d)— where R^(d) is —C₁₋₆ alkyl, and R⁶is —C₁₋₈ alkyl, —C₂₋₈ alkenyl or —C₂₋₈ alkynyl, each of which isoptionally substituted with one or two R^(6c). In some embodiments,R^(6c) is —C₁₋₈ alkyl or —NR^(6d)R^(6e), where R^(6d) and R^(6e) areindependently —C₁₋₈ alkyl (preferably —C₁₋₃ alkyl). In some embodiments.L²-R⁶ is (2-(dimethylamino)ethyl)(methyl)amino.

Definition of L²-R⁶, Wherein L² is a Direct Bond and R⁶ is Cycloalkyl,Heterocyclyl, Aryl or Heteroaryl

In some embodiments, L² is a direct bond, and R⁶ is cycloalkyl,heterocyclyl, aryl or heteroaryl, each of which is independently andoptionally substituted with one or two or three substituents R^(6c).

In some embodiments, L² is a direct bond, and R⁶ is heterocyclyl, whichis optionally substituted with one or two or three substituents R^(6c).

As R⁶, in some embodiments, the heterocyclyl is monocyclic; in someembodiments, the heterocyclyl is fused bicyclic heterocyclyl; and insome embodiments, the heterocyclyl is spirobicyclic heterocyclyl.

In some embodiments, the heterocyclyl is saturated. In some embodiments,the heterocyclyl is a 4-, 5-, 6-, 7-, or 8-membered saturated monocyclicring, which comprises one, two or three heteroatoms selected fromoxygen, nitrogen or optionally oxidized sulfur as ring members. In someembodiments, the heterocyclyl is a 5-, 6-, 7- or 8-membered saturatedmonocyclic ring comprising one or two or three nitrogen heteroatoms asring members. In some embodiments, the heterocyclyl is a 5- or6-membered saturated monocyclic ring comprising one or two nitrogenheteroatoms as ring members. In some embodiments, the heterocyclyl ispyrrolidinyl (e.g., pyrrolidin-1-yl, pyrrolidin-2-yl, pyrrolidin-3-yl),piperidinyl (e.g., piperidin-1-yl, piperidin-2-yl, piperidin-3-yl,piperidin-4-yl, piperidin-5-yl), triazolyl (e.g.,1H-1,2,4-triazol-1-yl), azepanyl (e.g., azepan-2-yl, azepan-3-yl,azepan-4-yl, azepan-5-yl), diazepinyl (e.g., 1,4-diazepin-1-yl,1,4-diazepin-2-yl, 1,4-diazepin-3-yl, 1,4-diazepin-4-yl), piperazinyl(e.g., piperazin-1-yl, piperazin-2-yl, piperazin-3-yl), or morpholino.

In some embodiments, the heterocyclyl is bicyclic and comprises one, twoor three heteroatoms selected from oxygen, nitrogen or optionallyoxidized sulfur as ring members. In some examples, the heterocyclyl is2,5-diazabicyclo[2.2.1]hept-2-yl.

In some embodiments, the heterocyclyl is 6-14-membered, and morepreferably 7-10-membered spirobicyclic heterocyclyl. In someembodiments, the heterocyclyl is spiroheptyl, spirodecyl or spirononylcomprising one or two nitrogen atoms as ring members. In someembodiments, the heterocyclyl is 8-azaspiro[4.5]dec-8-yl,2,7-diazspiro[3.5]non-7-yl, 2,8-diazspiro[4.5]dec-2-yl,2,7-diazspiro[3.5]non-2-yl, and 2,8-diazspiro[4.5]dec-8-yl.

In the above embodiments, the heterocyclyl as R⁶ is further optionallysubstituted with one or two substituents R^(6c).

In some embodiments, R^(6c) is —COR^(6d), wherein R^(6d) is —C₁₋₈ alkyloptionally substituted with one or two substituents R^(6g), whereinR^(6g) is —NR^(6h)R^(6i), —N(R^(6h))C(═O)R^(6i), —C₁₋₈ alkyl, aryl orheteroaryl, wherein R^(6h) and R^(6i) are as defined for formula (I). Insome embodiments, R^(6c) is —COR^(6d), wherein R^(6d) is —C₁₋₈ alkyl(preferably C₁₋₆ alkyl, and more preferably C₁₋₄ alkyl) optionallysubstituted with one or two substituents R^(6g), wherein R^(6g) is—NR^(6h)R^(6i), —N(R^(6h))C(═O)R^(6i), —C₁₋₈ alkyl, aryl or heteroaryl,wherein R^(6h) and R^(6i) are each independently hydrogen or —C₁₋₈ alkyl(preferably C₁₋₆ alkyl, and more preferably C₁₋₄ alkyl).

In some embodiments, R^(6c) is —COR^(6d), wherein R^(6d) is —C₂₋₈alkenyl.

In some embodiments, R^(6c) is —COR^(6d), wherein R^(6d) isheterocyclyl.

In some embodiments, R^(6c) is acetyl, 2-(dimethylamino)acetyl,2-(dimethylamino)acetyl, aminoacetyl, 2-(methylamino)acetyl,3-(dimethylamino)propionyl, 4-(dimethylamino)butyryl,5-(dimethylamino)valeryl, (2S,3S)-2-amino-3-methylvaleryl,2-(methylamino)acetyl, 2-amino-4-methylvaleryl, 2-amino-3-methylbutyryl,2-(dimethylamino)acetyl, phenylpropionyl, 2-(piperazin-1-yl)acetyl,acryloyl, piperazin-2-carbonyl, piperidin-4-carbonyl,pyrrolidin-2-carbonyl or 2-(N-methylacetamino)acetyl.

In some embodiments, R^(6c) is —C₁₋₈ alkoxy, preferably —C₁₋₆ alkoxy,such as methoxy.

In some embodiments, R^(6c) is —C₁₋₈ alkyl, preferably —C₁₋₆alkyl, whichis optionally substituted with one or two substituents R^(6g), whereinR^(6g) is —OR^(6h), —NR^(6h)R^(6i), heterocyclyl, aryl, wherein R^(6h)and R^(6i) are as defined for formula (I). In some aspects, R^(6c) is—C₁₋₈ alkyl, preferably —C₁₋₆ alkyl, which is optionally substitutedwith a substituent R^(6g), wherein R^(6g) is —OR^(6h), —NR^(6h)R^(6i),heterocyclyl (e.g., morpholino), aryl (e.g., phenyl), wherein R^(6h) andR^(6i) are —C₁₋₄ alkyl, and preferably methyl. In some embodiments,R^(6c) is methyl, ethyl, isobutyl, methoxymethyl, 2-methoxyethyl,(methylamino)methyl, 2-(dimethylamino)ethyl, (dimethylamino)methyl,2-aminoethyl, 2-(methylamino)ethyl 2-(dimethylamino)ethyl,morpholinomethyl or phenethyl.

In some embodiments, R^(6c) is heterocyclyl, which is optionallysubstituted with a substituent R^(6g). In some embodiments, R^(6c) isheterocyclyl, which is optionally substituted with a substituent R^(6g)which is heterocyclyl. In some embodiments, R^(6c) is4-morpholinopiperidin-1-yl.

In some embodiments, R^(6c) is —C(═O)NR^(6d)R^(6e), wherein R^(6d) andR^(6e) are independently hydrogen, —C₁₋₈ alkyl (preferably —C₁₋₃ alkyl)or aryl, wherein the —C₁₋₈ alkyl or aryl is independently and optionallysubstituted with halogen or —C₁₋₄ alkyl. In some embodiments, R^(6c) is—C(═O)NR^(6d)R^(6e), wherein R^(6d) and R^(6e) are independentlyhydrogen and —C₁₋₄ alkyl. In some embodiments, R^(6c) is—C(═O)NR^(6d)R^(6e), wherein R^(6d) and R^(6e) are independentlyhydrogen and aryl optionally substituted with halogen. In someembodiments, R^(6c) is dimethylcarbamoyl, isopropylcarbamoyl or2,4,5-trifluorophenylcarbamoyl.

In some embodiments, R^(6c) is —NR^(6d)R^(6e), wherein R^(6d) and R^(6e)are independently hydrogen or —C₁₋₈ alkyl (preferably —C₁₋₆ alkyl, morepreferably —C₁₋₃ alkyl, and most preferably methyl). In someembodiments, R^(6e) is dimethylamino or amino.

In some embodiments, R^(6c) is —SO₂R^(6d), wherein R^(6d) is —C₁₋₈alkyl, —C₂₋₈ alkenyl, —C₂₋₈ alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl or heteroaryl. In some embodiments,R^(6c) is —SO₂R^(6d), wherein R^(6d) is —C₁₋₈ alkyl (preferably —C₁₋₆alkyl). In some embodiments, R^(6c) is propylsulfonyl.

In some embodiments, L² is a direct bond, and R⁶ is pyrrolidinyl, whichis optionally substituted with one or two or three substituents selectedfrom methyl, (dimethylamino)methyl or dimethylamino.

In some embodiments, L² is a direct bond, and R⁶ is piperazinyl, whichis optionally substituted with one or two or three substituents selectedfrom: acryloyl, 2-(dimethylamino)acetyl, aminoacetyl,2-(methylamino)acetyl, 3-(dimethylamino)propionyl,2-(piperazin-1-yl)acetyl, piperazin-2-carbonyl,4-(dimethylamino)butyryl, 5-(dimethylamino)valeryl, methyl,piperidin-4-carbonyl, acetyl, 2-(N-methylacetamino)acetyl,isopropylcarbamoyl, 2,4,5-trifluorophenylcarbamoyl,(2S,3S)-2-amino-3-methylvaleryl, 2-methoxyethyl, 2-(methylamino)acetyl,ethyl, isobutyl, pyrrolidin-2-carbonyl, 2-amino-4-methylvaleryl,2-amino-3-methylbutyryl, 2-(dimethylamino)acetyl, 2-(methylamino)ethyl,2-(dimethylamino)ethyl, amino, phenylpropionyl, propylsulfonyl or2-aminoethyl.

In some embodiments, L² is a direct bond, and R⁶ is piperidyl,optionally substituted with one or two or three substituents selectedfrom: 2-(dimethylamino)acetyl, methoxy, methoxymethyl,(methylamino)methyl, 4-morpholinopiperidin-1-yl, morpholinomethyl,2-(dimethylamino)ethyl, phenethyl, (dimethylamino)methyl, amino,dimethylamino or dimethylcarbamoyl.

Definitions of ring A, R⁵ and L²-R⁶

In some embodiments, ring A is azetidin-3-yl, azepan-4-yl;piperidin-2-yl, piperidin-3-yl, piperidin-4-yl; pyrrolidin-1-yl,pyrrolidin-2-yl, pyrrolidin-3-yl: piperazin-1-yl;7-azaspiro[3.5]non-2-yl, 2-azaspiro[3.3]hept-6-yl,7-azaspiro[3.5]non-2-yl, 2-azaspiro[3.5]non-7-yl;3-azabicyclo[3.1.0]hex-6-yl, 2-azabicyclo[2.2.1]hept-5-yl,8-azabicyclo[3.2.1]oct-3-yl, 2-azabicyclo[4.1.0]hept-5-yl: cyclobutyl,bicyclo[1.1.1]pent-1-yl; bicyclo[1.1.1]pent-1-yl; or1,2,3,6-tetrahydropyridin-4-yl. In some embodiments, ring A ispiperidinyl, preferably piperidin-1-yl or piperidin-4-yl.

p is 0 or 1.

In some embodiments, R⁵ and L²-R⁶ are each independently methyl, ethyl,isopropyl; 2-(methylamino)ethyl; benzyl; piperidin-4-yl-methyl;(methylamino)methyl: 2-(methylamino)ethyl; hydroxymethyl;trifluoromethyl; pyrrolidin-3-yl, pyrrolidin-2-yl, piperidin-4-yl:hydroxyl; oxo; fluorine; ethoxycarbonyl; phenyl; methylamino or amino.

In some embodiments, the moiety

is piperidin-4-yl, 1-methylpiperidin-4-yl,1-(2-(methylamino)ethyl)piperidin-4-yl,1-(pyrrolidin-3-yl)piperidin-4-yl, 1-(pyrrolidin-2-yl)piperidin-4-yl,1-(piperidin-4-yl)piperidin-4-yl, 4-methylpiperidin-4-yl,3-hydroxypiperidin-4-yl, 3-oxopiperidin-4-yl, 3-fluoropiperidin-4-yl,3,3-difluorpiperidin-4-yl, 3-benzylpiperidin-4-yl,1-(piperidin-4-ylmethyl)piperidin-4-yl,4-((methylamino)methyl)piperidin-1-yl, 2-ethylpiperidin-4-yl,2-ethoxycarbonylpiperidin-4-yl, 2-hydroxymethylpiperidin-4-yl,1-methyl-2-((methylamino)methyl)piperidin-4-yl,1-isopropyl-2-((methylamino)methyl)piperidin-4-yl,2,6-dimethylpiperidin-4-yl, 2,2-dimethylpiperidin-4-yl,2-(trifluoromethyl)piperidin-4-yl, 2-phenylpiperidin-4-yl,4-(methylamino)piperidin-1-yl; piperidin-2-yl; pyrrolidin-3-yl;azetidin-3-yl: azepan-4-yl; (R)-3-methylpiperazin-1-yl;(S)-3-methylpiperazin-1-yl; (S)-3-methylpiperazin-1-yl;(R)-3-methylpiperazin-1-yl; 2-hydroxy-7-azaspiro[3.5]non-2-yl3-azabicyclo[3.1.0]hex-6-yl; 2-azaspiro[3.3]hept-6-v;7-azaspiro[3.5]non-2-yl; 2-azaspiro[3.5]non-7-yl;2-azabicyclo[2.2.1]hept-5-yl; 8-azabicyclo[3.2.1]oct-3-yl;3-aminocyclobutyl; 1-(2-(methylamino)ethyl)-2-oxo-piperidin-4-yl;2-azabicyclo[4.1.0]hept-5-yl; 1,2,3,6-tetrahydropyridin-4-yl;3-aminobicyclo[1.1.1]pent-1-yl;3-((methylamino)methyl)bicyclo[1.1.1]pent-1-yl.

In second aspect, the invention discloses a compound of formula (II),

or a pharmaceutically acceptable salt thereof, or a stereoisomerthereof, wherein:

R^(a) and R^(b) in each occurrence are independently hydrogen, halogen,alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl, heteroaryl or —OR^(c);

wherein R^(c) is hydrogen, alkyl, alkoxy-alkyl-, alkenyl, alkynyl,cycloalkyl, aryl, heterocyclyl or heteroaryl:

R¹ is —OR^(1a), —SR^(1a), —NR^(1a)R^(1b), —COR^(1a), —SO₂R^(1a),—C(═O)OR^(1a), —C(═O)NR^(1a)R^(1b), —C(═NR^(1a))NR^(1b)R^(1c),—N(R^(1a))C(═O)R^(1b), —N(R^(1a))C(═O)OR^(1b),—N(R^(1a))C(O)NR^(1b)R^(1c), —N(R^(1a))S(O)NR^(1b)R^(1c),—N(R^(1a))S(O)₂NR^(1b)R^(1c), —NR^(1a)SO₂R^(1b), alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl, orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachindependently and optionally substituted with one or two or threesubstituents R^(1d).

R^(1a), R^(1b) and R^(1c) are independently hydrogen, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachoptionally substituted with one or two or three substituents selectedfrom: halogen, —C₁₋₈ alkyl optionally substituted with R^(1e),cycloalkyl optionally substituted with R^(1e), heterocyclyl optionallysubstituted with R^(1e), aryl optionally substituted with R^(1e),heteroaryl optionally substituted with R^(1e), CH₃—(OCH₂CH₂)_(n)— (wheren is 3 to 10) or —OR^(1f):

wherein R^(1e) is halogen, nitro, cyano, hydroxyl, amino (—NH₂),alkylamino, dialkylamino, —C₁₋₆ alkyl optionally substituted withhalogen, carboxyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl,and dialkylaminocarbonyl:

wherein R^(1f) is alkyl, cycloalkyl, heterocyclyl, aryl or heteroaryl,each of which is optionally substituted with —C₁₋₄ alkyl or halogen;

R^(1d) in each occurrence is independently hydrogen, oxo, —CN, —NO₂,hydroxyl, amino (—NH₂), alkylamino, dialkylamino, halogen, haloalkyl,alkyl, haloalkoxy, alkoxy, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl or heteroaryl;

ring A is a cycloalkyl or heterocyclyl ring;

Het is heterocyclyl;

R⁵ is halogen, hydroxyl, alkyl, haloalkyl, alkoxy, haloalkoxy or—C(═O)OR^(5a), wherein R^(5a) is hydrogen, alkyl or haloalkyl;

p is 0, 1, 2 or 3;

R^(6c) is independently hydrogen, halogen, cyano, —NO₂, —OR^(6d),—SR^(6d), —NR^(6d)R^(6e), —COR^(6d), —SO₂R^(6d), —C(═O)OR^(6d),—C(═O)NR^(6d)R^(6e), —C(═NR^(6d))NR^(6e)R^(6f), —N(R^(6d))C(═O)R^(6e),—N(R^(6d))C(═O)OR^(6e), —N(R^(6d))C(O)NR^(6e)R^(6f),—N(R^(6d))S(O)NR^(6e)R^(6f), —N(R^(6d))S(O)₂NR^(6e)R^(6f),—NR^(6d)SO₂R^(6e), alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl or heteroaryl, wherein the alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl are each independently and optionally substitutedwith one or two or three substituents R^(6g);

R^(6d), R^(6e) and R^(6f) are independently hydrogen, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl, wherein the alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachoptionally substituted with one or two or three substituents R^(6g);

R^(6g) in each occurrence is independently hydrogen, halogen, cyano,—NO₂, —OR^(6h), —SR^(6h), —NR^(6h)R^(6i), —COR^(6h), —SO₂R^(6h),—C(═O)OR^(6h), —C(═O)NR^(6h)R^(6i), —C(═NR^(6h))NR^(6i)R^(6j),—N(R^(6h))C(═O)R^(6i), —N(R^(6h))C(═O)OR^(6i),—N(R^(6h))C(O)NR^(6i)R^(6j), —N(R^(6h))S(O)NR^(6i)R^(6j),—N(R^(6h))S(O)₂NR^(6i)R^(6h), —NR^(6h)SO₂R^(6i), alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl,

R^(6h), R^(6i) and R^(6j) are independently hydrogen, alkyl, alkoxy,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl, wherein the alkyl, alkoxy, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroarylare each independently and optionally substituted with one or two orthree substituents selected from: halogen, —C₁₋₄alkyl, —C₁₋₄ alkoxy,hydroxyl, nitro, —NH₂, alkylamino, dialkylamino or cyano.

Definition of R¹

In some embodiments, R¹ is —OR^(1a) or —NR^(1a)R^(1b), wherein R^(1a)and R^(1b) are as defined for formula (II).

In some embodiments, R¹ is —OR^(1a) or —NR^(1a)R^(1b), wherein R^(1a)and R^(1b) are independently hydrogen, —C₁₋₈ alkyl or —C₂₋₈ alkenyl,wherein the —C₁₋₈ alkyl or —C₂₋₈ alkenyl is each optionally substitutedwith one or two or three substituents selected from: heterocyclyloptionally substituted with R^(1c), aryl optionally substituted withR^(1c), CH₃—(OCH₂CH₂)_(n)— (where n is 3 to 10, preferably 4-8, and morepreferably 5-7), or —OR^(1f);

wherein R^(1e) is halogen, —C₁₋₆ alkyl optionally substituted withhalogen, carboxyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl ordialkylaminocarbonyl,

wherein R^(1f) is —C₁₋₈ alkyl, aryl or heteroaryl, each of which isoptionally substituted with —C₁₋₄ alkyl or halogen.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is hydrogen.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C¹⁻⁸ alkyloptionally substituted with one or two or three substituents selectedfrom: halogen, —C₁₋₈ alkyl optionally substituted with R^(1e),cycloalkyl optionally substituted with R^(1e), heterocyclyl optionallysubstituted with R^(1e), aryl optionally substituted with R^(1e),heteroaryl optionally substituted with R^(1e), CH₃—(OCH₂CH₂)_(n)— (wheren is 3 to 10), or —OR^(1f), wherein R^(1e) and R^(1f) are as defined forformula (II).

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is substituted C₁₋₈alkyl. In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is linear. Insome embodiments, R¹ is —OR^(1a), wherein R^(1a) is branched alkyl. Insome embodiments, R¹ is —OR^(1a), wherein R^(1a) is branched alkyl,preferably —C₄₋₈ alkyl group, wherein the branched substituent is at theα position relative to the oxygen atom, including but not limited tobut-2-yl, pent-2-yl, pent-3-yl, hept-2-yl, hept-3-yl, hept-4-yl,oct-2-yl, oct-3-yl, oct-4-yl, or oct-5-yl. In some embodiments, R¹ ismethoxy, ethoxy, propoxy, butoxy, pentoxy, hexyloxy, heptyloxy oroctoxy. In some embodiments, R¹ is preferably propoxy, isopropoxy,n-butoxy, isobutoxy, but-2-yloxy (sec-butoxy), pent-2-yloxy,pent-3-yloxy, 2-methylbutoxy, hep-2-yloxy, hep-3-yloxy, hep-4-yloxy,oct-2-yloxy, oct-3-yloxy, oct-4-yloxy, or oct-5-yloxy. In someembodiments, R¹ is n-butoxy, but-2-yloxy (sec-butoxy), pent-2-yloxy,pent-3-yloxy, hept-2-yloxy, hept-3-yloxy, hept-4-yloxy, oct-2-yloxy,oct-3-yloxy, oct-4-yloxy, or oct-5-yloxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl, andpreferably —C₄₋₅ alkyl, wherein the alkyl is substituted with 1-3halogens, such as fluorine.

In some embodiments, R¹ is —OR^(1a), where R^(1a) is —C₁₋₈ alkyl, andpreferably —C₁₋₃ alkyl, wherein the alkyl is substituted with cycloalkyloptionally substituted with R^(1e), heterocyclyl optionally substitutedwith R^(1e), aryl optionally substituted with R^(1e) or heteroaryloptionally substituted with R^(1e), wherein R^(1e) is as defined forformula (II).

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl, andpreferably —C₁₋₃ alkyl, wherein the alkyl is substituted withheteroaryl, such as 5-6-membered heteroaryl comprising one or two orthree heteroatoms selected from oxygen, nitrogen or optionally oxidizedsulfur as ring members, wherein the heteroaryl is optionally substitutedwith —C₁₋₆ alkyl, preferably —C₁₋₄ alkyl, and more preferably methyl. Insome embodiments, the heteroaryl is pyridinyl or imidazolyl orisoxazolyl. In some embodiments, R¹ is pyridin-3-ylmethoxy,2-(1H-imidazol-1-yl)ethoxy or (5-methylisoxazol-3-yl)methoxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl, andpreferably —C₁₋₃ alkyl, wherein the alkyl is substituted with aryl suchas phenyl. In some embodiments, R¹ is 2-phenylethoxy or 3-phenylpropoxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl, andpreferably —C₁₋₃ alkyl, wherein the alkyl is substituted with —OR^(1f),wherein R^(1f) is —C₁₋₈ alkyl or aryl (e.g., phenyl). In someembodiments, R¹ is 2-methoxyethoxy or 2-phenoxyethoxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl, andpreferably —C₁₋₃ alkyl, wherein the alkyl is substituted withCH₃—(OCH₂CH₂)_(n)—, where n is 3 to 10, preferably 3 or 4 or 5. In someembodiments, R¹ is 2,5,8,11-tetraoxatridec-13-yloxy.

In some embodiments, R¹ is —OR^(1a), wherein R^(1a) is —C₂₋₈ alkenyl;preferably —C₂₋₆ alkenyl; and most preferably —C₄₋₆ alkenyl. In oneexample, R¹ is but-3-enyloxy.

In some embodiments, R¹ is —NR^(1a)R^(1b), wherein R^(1a) and R^(1b) areeach hydrogen or —C₁₋₈ alkyl, preferably —C₁₋₆ alkyl, wherein the alkylis optionally substituted with one or two or three substituents selectedfrom: halogen, —C₁₋₈ alkyl optionally substituted with R^(1e),cycloalkyl optionally substituted with R^(1e), heterocyclyl optionallysubstituted with R^(1e), aryl optionally substituted with R^(1e) orheteroaryl optionally substituted with R^(1e), wherein R^(1e) is —C₁₋₆alkyl, such as methyl.

In some embodiments, R¹ is —NR^(1a)R^(1b), where R^(1a) is hydrogen andR^(1b) is linear or branched —C₁₋₈ alkyl. In some embodiments, R¹ is—NR^(1a)R^(1b), wherein R^(1a) is hydrogen, R^(1b) is branched alkyl,preferably —C₄₋₈ alkyl, wherein the branched substituent is at the αposition relative to the oxygen atom, including but not limited tobut-2-yl, pent-2-yl, pent-3-yl, hept-2-yl, hept-3-yl, hept-4-yl,oct-2-yl, oct-3-yl, oct-4-yl, or oct-5-yl.

In some embodiments, R¹ is butylamino, N-butyl-N-methylamino orisopentylamino.

In some embodiments, R¹ is optionally partially or completelydeuterated, that is, one or more carbon-bonded hydrogen atoms in thedefinition of R¹ are replaced by one or more deuterium atoms.

Definition of R⁵

In some embodiments, R⁵ is halogen, oxo, hydroxyl, C₁₋₈ alkyl,halogenated C₁₋₈ alkyl, C₁₋₈ alkoxy, halogenated C₁₋₈ alkoxy, or—C(═O)OR^(5a), wherein R^(5a) is hydrogen, C₁₋₈ alkyl, or halogenatedC₁₋₈ alkyl; and p is 0, 1, or 2.

In some embodiments, R⁵ is halogen, oxo, C₁₋₃ alkyl, halogenated C₁₋₃alkyl, C₁₋₃ alkoxy, or halogenated C₁₋₈ alkoxy. In some embodiments, R⁵is methyl, ethyl, propyl, methoxy, ethoxy, propoxy, isopropoxy,trifluoromethoxy or trifluoromethyl. In some embodiments, R⁵ is methyl.

In some embodiments, p is 1.

In some embodiments, R⁵ and Het-R^(6c) are on ortho-positions of ring A.

Definition of Ring A

In some embodiments, ring A is heterocyclyl.

In some embodiments, ring A is 4-, 5-, 6-, 7-, 8- or 9-memberedmonocyclic heterocyclyl, which comprises one or two or three heteroatomsselected from oxygen, nitrogen or optionally oxidized sulfur as ringmembers; preferably 5- or 6-membered heteroaryl comprising one or twonitrogen atoms as ring members; and more preferably, 5- or 6-memberedheteroaryl comprising one nitrogen atom as a ring member. In someembodiments, ring A is azetidinyl (e.g., azetidin-1-yl, azetidin-2-yl,azetidin-3-yl, azetidin-4-yl), pyrrolidinyl (e.g., pyrrolidin-1-yl,pyrrolidin-2-yl, pyrrolidin-3-yl), piperidinyl (e.g., piperidin-1-yl,piperidin-2-yl, piperidin-3-yl, piperidin-4-yl), or azepanyl (e.g.,azepan-1-yl, azepan-2-yl, azepan-3-yl, azepan-4-yl); and preferablypiperidinyl (e.g., piperidin-1-yl, piperidin-4-yl). In some embodiments,ring A is piperazinyl (e.g., piperazin-1-yl or piperazin-2-yl).

In some embodiments, the heterocyclyl ring may comprise one or moredouble bonds (C═C or C═N), but it is not aromatic. However, theheterocyclyl ring is preferably saturated.

In some embodiments, ring A is spiro heterocyclyl or bridgedheterocyclyl, such as 5-20-membered, preferably 6-14-membered, and morepreferably 7-12-membered heterocyclyl. In some embodiments, theheterocyclyl is 7-azaspiro[3.5]nonyl, 3-azaspiro[3.1.0]hexyl,2-azaspiro[3.3]heptyl, 7-azaspiro[3.5]nonyl, 2-azaspiro[3.5]nonyl,2-azabicyclo[2.2.1]heptyl, 8-azabicyclo[3.2.1]octyl or2-azabicyclo[4.1.0]heptyl. More specifically, the spiro heterocyclyl is7-azaspiro[3.5]non-2-yl, 3-azabicyclo[3.1.0]hex-6-yl,2-azaspiro[3.3]hept-6-yl, 7-azaspiro[3.5]non-2-yl,2-azaspiro[3.5]non-7-yl, 2-azabicyclo[2.2.1]hept-5-yl,8-azabicyclo[3.2.1]oct-3-yl or 2-azabicyclo[4.1.0]hept-5-yl.

In some embodiments, ring A is a cycloalkyl ring, such as 3-8-memberedmonocyclic cycloalkyl or 6-12-membered bicyclic cycloalkyl selected fromspiro-cycloalkyl, fused cycloalkyl or bridged cycloalkyl, such asbicyclo[1.1.1]pentyl (e.g., bicyclo[1.1.1]pent-1-yl). In someembodiments, ring A is cycloalkenyl or cycloalkynyl.

Definition of Het

In some embodiments, Het is monocyclic heterocyclyl; in someembodiments, Het is fused bicyclic heterocyclyl: in some embodiments,Het is spirobicyclic heterocyclyl.

In some embodiments. Het is saturated heterocyclyl. In some embodiments,Het is a 4-, 5-, 6-, 7-, or 8-membered saturated monocyclic heterocyclylring, which comprises one, two or three heteroatoms selected fromoxygen, nitrogen or optionally oxidized sulfur as ring members. In someembodiments, Het is a 5-, 6-, 7- or 8-membered saturated monocyclicheterocyclyl ring comprising one or two or three nitrogen heteroatoms asring members. In some embodiments, Het is a 5- or 6-membered saturatedmonocyclic heterocyclyl ring comprising one or two nitrogen heteroatomsas ring members. In some embodiments, Het is pyrrolidinyl (e.g.,pyrrolidin-1-yl, pyrrolidin-2-yl, pyrrolidin-3-yl), piperidinyl (e.g.,piperidin-1-yl, piperidin-2-yl, piperidin-3-yl, piperidin-4-yl,piperidin-5-yl), triazolyl (e.g., 1H-1,2,4-triazol-1-yl), azepanyl(e.g., azepan-2-yl, azepan-3-yl, azepan-4-yl, azepan-5-yl), diazepinyl(e.g., 1,4-diazepin-1-yl, 1,4-diazepin-2-yl, 1,4-diazepin-3-yl,1,4-diazepin-4-yl), piperazinyl (e.g., piperazin-1-yl, piperazin-2-yl,piperazin-3-yl), or morpholino.

In some embodiments, Het is a bicyclic heterocyclyl ring comprising one,two or three heteroatoms selected from oxygen, nitrogen or optionallyoxidized sulfur as ring members. In some examples, Het is2,5-diazabicyclo[2.2.1]hept-2-yl.

In some embodiments, Het is 6-14-membered, and more preferably7-10-membered spirobicyclic heterocyclyl. In some embodiments, theheterocyclyl is spiroheptyl, spirodecyl or spirononyl comprising one ortwo nitrogen atoms as ring members. In some embodiments, theheterocyclyl is 8-azaspiro[4.5]dec-8-yl, 2,7-diazspiro[3.5]non-7-yl,2,8-diazspiro[4.5]dec-2-yl, 2,7-diazspiro[3.5]non-2-yl, and2,8-diazspiro[4.5]dec-8-yl.

Definition of R^(6c)

In some embodiments, Het is optionally substituted with one or two orthree substituents R^(c).

In some embodiments, Het is optionally substituted with one R^(6c).

In some embodiments, R^(6c) is independently hydrogen, halogen —OR^(6d),—SR^(6d), —NR^(6d)R^(6e), —COR^(6s), —SO₂R^(6d), —C(═O)NR^(6d)R^(6e) or—C₁₋₈ alkyl, wherein the —C₁₋₈ alkyl is independently and optionallysubstituted with one or two or three substituents R^(6g);

R^(6d) and R^(6e) are independently hydrogen, —C₁₋₈ alkyl, —C₂₋₈alkenyl, heterocyclyl or aryl, wherein the —C₁₋₈ alkyl, —C₂₋₈ alkenyl,heterocyclyl or aryl is each optionally substituted with one or two orthree substituents R^(6g);

R^(6g) in each occurrence is independently hydrogen, halogen. —OR^(6h),—SR^(6h), —NR^(6h)R^(6i), —N(R^(6h))C(═O)OR^(6i), —C₁₋₈ alkyl,heterocyclyl, aryl or heteroaryl,

R^(6h) and R^(6i) are independently hydrogen or —C₁₋₈ alkyl.

In some embodiments, R⁶ is —COR^(6d), wherein R^(6d) is —C₁₋₈ alkyloptionally substituted with one or two substituents R^(6g), whereinR^(6g) is —NR^(6h)R^(6i), —N(R^(6h))C(═O)R^(6i), —C₁₋₈ alkyl, aryl orheteroaryl, wherein R^(6h) and R^(6i) are as defined for formula (II).In some embodiments, R^(6c) is —COR^(6d), wherein R^(6d) is —C₁₋₄ alkyl(preferably C₁₋₄ alkyl, and more preferably C₁₋₄ alkyl) optionallysubstituted with one or two substituents R^(6g), where R^(6g) is—NR^(6h)R^(6i), —N(R^(6h))C(═O)R^(6i), —C₁₋₈ alkyl, aryl or heteroaryl,wherein R^(6h) and R^(6i) are each independently hydrogen or —C₁₋₈ alkyl(preferably C₁₋₆ alkyl, and more preferably C₁₋₄ alkyl).

In some embodiments, R^(6c) is —COR^(6d), wherein R^(6d) is —C₂₋₈alkenyl.

In some embodiments, R^(6c) is —COR^(6d), wherein R^(6d) isheterocyclyl.

In some embodiments, R^(6c) is acetyl, 2-(dimethylamino)acetyl,2-(dimethylamino)acetyl, aminoacetyl, 2-(methylamino)acetyl,3-(dimethylamino)propionyl, 4-(dimethylamino)butyryl,5-(dimethylamino)valeryl, (2S,3S)-2-amino-3-methylvaleryl,2-(methylamino)acetyl, 2-amino-4-methylvaleryl, 2-amino-3-methylbutyryl,2-(dimethylamino)acetyl, phenylpropionyl, 2-(piperazin-1-yl)acetyl,acryloyl, piperazin-2-carbonyl, piperidin-4-carbonyl,pyrrolidin-2-carbonyl or 2-(N-methylacetamino)acetyl.

In some embodiments, R^(6c) is —C₁₋₈ alkoxy, preferably —C₁₋₆ alkoxy,such as methoxy.

In some embodiments, R^(6c) is —C₁₋₈ alkyl, preferably —C₁₋₆ alkyl,which is optionally substituted with one or two substituents R^(6g),wherein R^(6g) is —OR^(6h), —NR^(6h)R^(6i), heterocyclyl, aryl, whereinR^(6h) and R^(6i) are as defined for formula (II). In some aspects.R^(6c) is —C₁₋₈ alkyl, preferably —C₁₋₆ alkyl, which is optionallysubstituted with a substituent R^(6g), wherein R^(6g) is —OR^(6i),—NR^(6h)R^(6i), heterocyclyl (e.g., morpholino), aryl (e.g., phenyl),wherein R^(6h) and R^(6i) are —C₁₋₄ alkyl, and preferably methyl. Insome embodiments, R^(6c) is methyl, ethyl, isobutyl, methoxymethyl,2-methoxyethyl, (methylamino)methyl, 2-(dimethylamino)ethyl,(dimethylamino)methyl, 2-aminoethyl, 2-(methylamino)ethyl2-(dimethylamino)ethyl, morpholinomethyl or phenethyl.

In some embodiments R^(6c) is heterocyclyl, which is optionallysubstituted with a substituent R^(6g). In some embodiments, R^(6c) isheterocyclyl, which is optionally substituted with a substituent R^(6g)which is heterocyclyl. In some embodiments, R^(6c) is4-morpholinopiperidin-1-yl.

In some embodiments, R^(6c) is —C(═O)NR^(6d)R^(6e), wherein R^(6d) andR^(6e) are independently hydrogen, —C₁₋₈ alkyl (preferably —C₁₋₃ alkyl)or aryl, wherein the —C₁₋₈ alkyl or aryl is independently and optionallysubstituted with halogen or —C₁₋₄ alkyl. In some embodiments, R^(6c) is—C(═O)NR^(6d)R^(6e), wherein R^(6d) and R^(6e) are independentlyhydrogen and —C₁₋₄ alkyl. In some embodiments, R^(6c) is—C(═O)NR^(6d)R^(6e), wherein R^(6d) and R^(6e) are independentlyhydrogen and aryl optionally substituted with halogen. In someembodiments, R^(6c) is dimethylcarbamoyl, isopropylcarbamoyl or2,4,5-trifluorophenylcarbamoyl.

In some embodiments, R^(6c) is —NR^(6d)R^(6e), wherein R^(6d) and R^(6e)are independently hydrogen or —C₁₋₈ alkyl (preferably —C₁₋₆ alkyl, morepreferably —C₁₋₃ alkyl, and most preferably methyl). In someembodiments, R^(6e) is dimethylamino or amino.

In some embodiments, R^(6c) is —SO₂R^(6d), wherein R^(6d) is —C₁₋₈alkyl, —C₂₋₈ alkenyl, —C₂₋₈ alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl or heteroaryl. In some embodiments,R^(6c) is —SO₂R^(6d), wherein R^(6d) is —C₁₋₈ alkyl (preferably —C₁₋₆alkyl). In some embodiments, R^(6c) is propylsulfonyl.

In some embodiments, Het is pyrrolidinyl, which is optionallysubstituted with one or two or three substituents selected from methyl,(dimethylamino)methyl or dimethylamino. In some embodiments, Het is1-methylpyrrolidin-3-yl, pyrrolidin-1-yl, 3-((dimethylamino)methyl)pyrrolidin-1-yl or 3-(dimethylamino)pyrrolidin-1-yl.

In some embodiments. Het is piperazinyl, optionally substituted with oneor two or three substituents selected from: acryloyl,2-(dimethylamino)acetyl, aminoacetyl, 2-(methylamino)acetyl,3-(dimethylamino)propionyl, 2-(piperazin-1-yl)acetyl,piperazin-2-carbonyl, 4-(dimethylamino)butyryl,5-(dimethylamino)valeryl, methyl, piperidin-4-carbonyl, acetyl,2-(N-methylacetamino)acetyl, isopropylcarbamoyl,2,4,5-trifluorophenylcarbamoyl, (2S,3S)-2-amino-3-methylvaleryl,2-methoxyethyl, 2-(methylamino)acetyl, ethyl, isobutyl,pyrrolidin-2-carbonyl, 2-amino-4-methylvaleryl, 2-amino-3-methylbutyryl,2-(dimethylamino)acetyl, 2-(methylamino)ethyl, 2-(dimethylamino)ethyl,amino, phenylpropionyl, propylsulfonyl or 2-aminoethyl. In someembodiments, Het is piperazin-1-yl, 4-acrylpiperazin-1-yl,4-(2-(dimethylamino)acetyl)piperazin-1-yl.(4-aminoacetyl)piperazin-1-yl, piperazin-1-yl,4-(2-(methylamino)acetylpiperazin-1-yl),4-(3-(dimethylamino)propionyl)piperazin-1-yl, 4-(2-(piperazin-1-yl)acetyl)piperazin-1-yl, 4-(piperazin-2-carbonyl)piperazin-1-yl,4-acryloylpiperazin-1-yl, 4-(4-(dimethylamino)butyryl)piperazin-1-yl,4-(5-(dimethylamino)valeryl)piperazin-1-yl, 3,5-dimethylpiperazin-1-yl,4-(piperidin-4-carbonyl)piperazin-1-yl, 4-acetylpiperazin-1-yl,4-(2-(N-methylacetylamino)acetyl)piperazin-1-yl,4-(isopropylcarbamoyl)piperazin-1-yl,4-(2,4,5-trifluorophenylcarbamoyl)piperazin-1-yl,4-(3,5-dimethylpiperazin-1-yl,4-((2S,3S)-2-amino-3-methylvaleryl)piperazin-1-yl,4(2-methoxyethyl)piperazin-1-yl,4-(2-(methylamino)acetyl)piperazin-1-yl, 4-ethylpiperazin-1-yl,4-isobutylpiperazin-1-yl, 4-(pyrrolidin-2-carbonyl)piperazin-1-yl,4-(2-amino-4-methylvaleryl)piperazin-1-yl,4-(2-amino-3-methylbutyryl)piperazin-1-yl,4-(2-(dimethylamino)acetyl)piperazin-1-yl, (S)-2-methylpiperazin-1-yl,(R)-2-methylpiperazin-1-yl, 4-(2-(methylamino)ethyl)piperazin-1-yl,4-(2-(dimethylamino)ethyl)piperazin-1-yl,4-(2-amino-3-phenylpropionyl)piperazin-1-yl,4-(propylsulfonyl)piperazin-1-yl, 4-(2-aminoethyl)piperazin-1-yl or3-methylpiperazin-1-yl.

In some embodiments, Het is piperidinyl, which is optionally substitutedwith one or two or three substituents selected from:2-(dimethylamino)acetyl, methoxy, methoxymethyl, (methylamino)methyl,4-morpholinopiperidin-1-yl, morpholinomethyl, 2-(dimethylamino)ethyl,phenethyl, (dimethylamino)methyl, amino, dimethylamino ordimethylcarbamoyl. In some embodiments, Het is piperidin-4-yl,4-(2-(dimethylamino)acetyl)piperidin-1-yl, piperidin-3-yl,piperidin-4-yl, piperidin-1-yl, piperidin-4-yl, 4-methoxypiperidin-1-yl,4-(methoxymethyl)piperidin-1-yl, 4-((methylamino)methyl)piperidin-1-yl,(4-morpholinopiperidin-1-yl)pyridin-3-yl,4-(morpholinomethyl)piperidin-1-yl,4-(2-(dimethylamino)ethyl)piperidin-1-yl, 1-phenethylpiperidin-4-yl,4-((dimethylamino)methyl)piperidin-1-yl, 4-aminopiperidin-1-yl,4-(dimethylamino)piperidin-1-yl or 4-(dimethylcarbamoyl)piperidin-1-yl.

In some embodiments, Het is azepan-1-yl or 1,4-diazepan-1-yl.

In some embodiments. Het is octahydro-2H-isoindol-2-yl.

In some embodiments, Het is morpholino.

In some embodiments, Het is 8-azaspiro[4.5]dec-8-yl,2,7-diazspiro[3.5]non-7-yl, 2,8-diazspiro[4.5]dec-2-yl,2,7-diazspiro[3.5]non-2-yl, 2,8-diazspiro[4.5]dec-8-yl,(1R,4R)-2,5-diazabicyclo[2.2.1]hept-2-yl.

In some embodiments, ring A is piperidinyl, preferably piperidin-1-yl orpiperidin-4-yl.

In some embodiments, the invention discloses a compound of formula(IIIA) or (IIIB),

or a pharmaceutically acceptable salt thereof, or a stereoisomerthereof,

wherein the variables R^(a), R^(b), L², R⁵, R⁶ and p are as definedabove.

In some embodiments, the invention discloses a compound selected fromthe specific compounds exemplified by the invention, or pharmaceuticallyacceptable salts thereof or stereoisomers thereof:

In third aspect, the invention discloses a pharmaceutical compositioncomprising the compounds disclosed herein, including compounds offormula (I) or (II) or specific compounds exemplified by the invention,or pharmaceutically acceptable salts thereof, and at least onepharmaceutically acceptable carrier or excipient.

In fourth aspect, the invention discloses a method for regulating TLR8,which comprises administering to an individual the compound disclosedherein or a pharmaceutically acceptable salt thereof, including thecompound of formula (I) or (II) or the specific compounds exemplified bythe invention.

In fifth aspect, the invention discloses a method for treating a diseaseor disorder in a patient, which comprises administering to the patient atherapeutically effective amount of the compound disclosed herein or apharmaceutically acceptable salt thereof as a TLR8 agonist, wherein thecompound disclosed herein includes a compound of formula (I) or (II) orthe specific compounds exemplified by the invention. In someembodiments, the disease or disorder is related to the regulation ofTLR, such as TLR-8 (e.g., the agitation of TLR-8). In some embodiments,the disease or disorder includes viral infections caused by virusesselected from dengue virus, yellow fever virus, west Nile virus,Japanese encephalitis virus, tick-borne encephalitis virus, kunjinvirus, Murray Valley encephalitis virus. St. Louis encephalitis virus,Omsk hemorrhagic fever virus, bovine viral diarrhea virus, Zika virusand hepatitis C. In some embodiments, the disease or disorder includesmelanoma, non-small cell lung cancer, hepatocellular carcinoma, basalcell carcinoma, renal cell carcinoma, myeloma, allergic rhinitis,asthma, COPD, ulcerative colitis, liver fibrosis, HBV, HCV, HPV, RSV,SARS, HIV or influenza. Preferably, the disease or disorder is cancer.

DETAILED DESCRIPTION OF THE INVENTION

The following terms have the meanings indicated throughout thespecification.

As used herein (including the appended claims), unless the contextclearly indicates otherwise, singular words such as “a”, “an” and “the”include their corresponding plural referents.

Unless the context clearly indicates otherwise, the term “or” is used tomean the term “and/or” and can be used interchangeably with the term“and/or”.

The term “alkyl” herein refers to a hydrocarbon group selected fromlinear saturated hydrocarbon groups and branched saturated hydrocarbongroups, which comprises 1 to 18 (such as 1 to 12, further such as 1 to10, still further such as 1 to 8 or 1 to 6 or 1 to 4) carbon atoms.

Examples of alkyl comprising 1 to 6 carbon atoms (i.e. C₁₋₆ alkyl)include, but are not limited to, methyl, ethyl, 1-propyl or n-propyl(“n-Pr”), 2-propyl or isopropyl (“i-Pr”), 1-butyl or n-butyl (“n-Bu”),2-methyl-1-propyl or isobutyl (“i-Bu”), 1-methylpropyl or sec-butyl(“s-Bu”), 1,1-dimethylethyl or tert-butyl (“t-Bu”), 1-pentyl, 2-pentyl,3-pentyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 3-methyl-1-butyl,2-methyl-1-butyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl-2-pentyl,3-methyl-2-pentyl, 4-methyl-2-pentyl, 3-methyl-3-pentyl,2-methyl-3-pentyl, 2,3-dimethyl-2-butyl and 3,3-dimethyl-2-butyl.

The term “alkoxy” or “alkyloxy” refers to the alkyl as previouslydefined which is attached to a parent molecular moiety through an oxygenatom.

The term “amino” refers to —NH₂. The term “alkylamino” refers to—NH(alkyl). The term “dialkylamino” refers to —N(alkyl)₂. As usedherein, the term “halogen” refers to fluorine (F), chlorine (Cl),bromine (Br) and iodine (I).

As used herein, the term “haloalkyl” refers to an alkyl group in whichone or more hydrogen atoms are replaced by one or more halogen atoms(e.g., fluorine, chlorine, bromine and iodine).

Examples of haloalkyl include halogenated C₁₋₈ alkyl, halogenated C₁₋₆alkyl or halogenated C₁₋₄ alkyl, but are not limited to —CF₃, —CH₂Cl,—CH₂CF₃, —CCl₂, CF₃ etc.

As used herein, the term “alkenyl” refers to a hydrocarbon groupselected from linear hydrocarbon groups and branched hydrocarbon groups,which comprises at least one C═C double bond and 2 to 18 (such as 2 to8, further such as 2 to 6) carbon atoms. Examples of alkenyl such asC₂₋₆ alkenyl include, but are not limited to, ethenyl (or vinyl),prop-1-enyl, prop-2-enyl, 2-methylprop-1-enyl, but-1-enyl, but-2-enyl,but-3-enyl, buta-1,3-dienyl, 2-methylbuta-1,3-dienyl, hex-1-enyl,hex-2-enyl, hex-3-enyl, hex-4-enyl and hexa-1,3-dienyl.

The term “alkynyl” herein refers to a hydrocarbon group selected fromlinear hydrocarbon groups and branched hydrocarbon groups, whichcomprises at least one C═C triple bond and 2 to 18 (such as 2 to 8,further such as 2 to 6) carbon atoms. Examples of alkynyl such as C₂₋₆alkynyl include but are not limited to ethynyl, 1-propynyl, 2-propynyl(propargyl), 1-butynyl, 2-butynyl and 3-butynyl.

As used herein, the term “alkyloxy” or “alkoxy” refers to the alkyl asdefined above which is attached to a parent molecular moiety through anoxygen atom. Examples of alkoxy such as C₁₋₆ alkoxy or C1-4 alkoxyinclude but are not limited to methoxy, ethoxy, isopropoxy, propoxy,n-butoxy, tert-butoxy, pentoxy and hexyloxy, etc.

The term “alkoxy-alkyl-” refers to the alkyl as defined above which isfurther substituted with the alkoxy as defined above. Examples ofalkoxy-alkyl- such as C1-8 alkoxy-C1-8 alkyl- or C1-6 alkoxy-C₁₋₆ alkyl-include but are not limited to methoxymethyl, ethoxymethyl, ethoxyethyl,isopropoxymethyl or propoxymethyl, etc.

The term “cycloalkyl” refers to a hydrocarbon group selected fromsaturated cyclic hydrocarbon groups, which includes monocyclic andpolycyclic (such as bicyclic and tricyclic) groups, including fused,bridged or spiro cycloalkyl.

For example, cycloalkyl may comprise 3 to 12 (such as 3 to 10, furthersuch as 3 to 8, further such as 3 to 6, 3 to 5 or 3 to 4) carbon atoms.Even further, for example, cycloalkyl can be selected from monocyclicgroups comprising 3 to 12 (such as 3 to 10, further such as 3 to 8, 3 to6) carbon atoms. Examples of monocyclic cycloalkyl include cyclopropyl,cyclobutyl, cyclopentyl, 1-cyclopent-1-enyl, 1-cyclopent-2-enyl,I-cyclopent-3-enyl, cyclohexyl, 1-cyclohex-1-enyl, 1-cyclohex-2-enyl,1-cyclohex-3-enyl, cyclohexadienyl, cycloheptyl, cyclooctyl, cyclononyl,cyclodecyl, cycloundecyl and cyclododecyl. Particularly, examples ofsaturated monocyclic cycloalkyl such as C₃₋₈ cycloalkyl include but arenot limited to cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl and cyclooctyl. In a preferred embodiment, cycloalkyl is amonocyclic ring comprising 3 to 6 carbon atoms (abbreviated as C₃₋₆cycloalkyl), which includes but is not limited to cyclopropyl,cyclobutyl, cyclopentyl and cyclohexyl. Examples of bicyclic cycloalkylinclude those having 7 to 12 ring atoms, which are arranged as fusedbicyclic rings selected from [4,4], [4,5], [5,5], [5,6] or [6,6] ringsystems, or bridged bicyclic rings selected from bicyclo[2.2.1]heptane,bicyclo[2.2.2]octane, and bicyclo[3.2.2]nonane. Other examples ofbicyclic cycloalkyl include those arranged as bicyclic rings selectedfrom [5,6] and [6,6] ring systems.

The term “spiro-cycloalkyl” includes a cyclic structure comprisingcarbon atoms and formed by at least two rings sharing one atom. The term“7-12-membered spiro-cycloalkyl” includes a cyclic structure comprising7 to 12 carbon atoms and formed by at least two rings sharing one atom.

The term “fused cycloalkyl” includes bicyclic cycloalkyl as definedherein, which is saturated and formed by two or more rings sharing twoadjacent atoms.

The term “bridged cycloalkyl” includes a cyclic structure comprisingcarbon atoms and formed by two rings sharing two atoms that are notadjacent to each other. The term “7-10-membered bridged cycloalkyl”includes a cyclic structure comprising 7 to 12 carbon atoms and formedby two rings sharing two atoms that are not adjacent to each other.

The term “cycloalkenyl” refers to a non-aromatic cyclic alkyl group with3 to 10 carbon atoms having one or more rings and at least one doublebond and preferably 1-2 double bonds. In one embodiment, thecycloalkenyl is cyclopentenyl or cyclohexenyl, preferably cyclohexenyl.

The term “cycloalkynyl” refers to a non-aromatic cycloalkyl group with 5to 10 carbon atoms having one or more rings and at least one triplebond.

The term “deuterated” is used here to modify chemical structures ororganic groups, in which one or more hydrogen atoms bonded to carbon arereplaced by one or more deuterium atoms, such as deuterated alkyl,deuterated cycloalkyl, deuterated heterocycloalkyl, deuterated aryl,deuterated morpholinyl, etc. For example, the term “deuterated alkyl”defined above refers to alkyl as defined herein, in which at least onehydrogen atom bonded to carbon is replaced by deuterium. In thedeuterated alkyl, at least one carbon atom is bonded to deuterium: thecarbon atom can be bonded with more than one deuterium atoms; more thanone carbon atoms in the alkyl group can also be bonded to deuterium.

The term “aryl” used alone or in combination with other terms refers toa group selected from:

5- and 6-membered carbocyclic aromatic rings such as phenyl;

bicyclic systems, such as 7-12-membered bicyclic systems, in which atleast one ring is carbocyclic and aromatic, such as naphthyl andindenyl; and

tricyclic systems, such as 10-15-membered tricyclic systems, in which atleast one ring is carbocyclic and aromatic, such as fluorenyl.

The terms “aromatic hydrocarbon ring” and “aryl” are usedinterchangeably in the disclosure herein. In some embodiments,monocyclic or bicyclic aromatic hydrocarbon rings have 5 to 10ring-forming carbon atoms (i.e., C₅₋₁₀ aryl). Examples of monocyclic orbicyclic aromatic hydrocarbon rings include, but are not limited to,phenyl, naphthalen-1-yl, naphthalen-2-yl, anthracyl, phenanthryl, etc.In some embodiments, the aromatic hydrocarbon ring is a naphthalene ring(naphthalen-1-yl or naphthalen-2-yl) or a benzene ring. In someembodiments, the aromatic hydrocarbon ring is a benzene ring.

As used herein, the term “heteroaryl” refers to a group selected from:5-, 6- or 7-membered aromatic monocyclic rings comprising at least oneheteroatom, such as 1 to 4 heteroatoms, or 1 to 3 heteroatoms in someembodiments and 1 to 2 heteroatoms in some embodiments, wherein theheteroatoms are selected from nitrogen (N), sulfur (S) and oxygen (O),and the remaining ring atoms are carbon:

7-12-membered bicyclic rings comprising at least one heteroatom, such as1 to 4 heteroatoms, or 1 to 3 heteroatoms in some embodiments, or 1 or 2heteroatoms in other embodiments, wherein the heteroatoms are selectedfrom nitrogen, oxygen or optionally oxidized sulfur (as one or more ringmembers), the remaining ring atoms are carbon, and at least one ring isaromatic and there is at least one heteroatom in the aromatic ring; and

11-14-membered tricyclic rings comprising at least one heteroatom, suchas 1 to 4 heteroatoms, or 1 to 3 heteroatoms in some embodiments, or 1or 2 heteroatoms in other embodiments, wherein the heteroatoms areselected from nitrogen, oxygen or optionally oxidized sulfur (as one ormore ring members), and the remaining ring atoms are carbon, and whereinat least one ring is aromatic and there is at least one heteroatom inthe aromatic ring.

When the total number of S and O atoms in the heteroaryl exceeds 1,these heteroatoms are not adjacent to each other. In some embodiments,the total number of S and O atoms in the heteroaryl is not more than 2.In some embodiments, the total number of S and O atoms in the aromaticheterocyclic ring is not more than 1. When the heteroaryl comprises morethan one heteroatom ring members, the heteroatoms may be the same ordifferent. Nitrogen atoms in one or more rings of the heteroaryl can beoxidized to form N-oxides.

As used herein, the term “optionally oxidized sulfur” refers to S, SO orSO₂.

The terms “aromatic heterocyclic ring” and “heteroaryl” are usedinterchangeably in the disclosure herein. In some embodiments, themonocyclic or bicyclic aromatic heterocyclic ring has 5, 6, 7, 8, 9 or10 ring-forming members, in which 1, 2, 3 or 4 heteroatom ring membersare independently selected from nitrogen (N), sulfur (S) and oxygen (O),and the remaining ring members are carbon. In some embodiments, themonocyclic or bicyclic aromatic heterocyclic ring is a monocyclic orbicyclic ring comprising 1 or 2 heteroatom ring members independentlyselected from nitrogen (N), sulfur (S) and oxygen (O). In someembodiments, the monocyclic or bicyclic aromatic heterocyclic ring is a5-6-membered heteroaryl ring which is monocyclic and has 1 or 2heteroatom ring members independently selected from nitrogen (N), sulfur(S) and oxygen (O). In some embodiments, the monocyclic or bicyclicaromatic heterocyclic ring is an 8-10-membered heteroaryl ring, which isbicyclic and has 1 or 2 heteroatom ring members independently selectedfrom nitrogen, sulfur and oxygen.

Examples of heteroaryl or monocyclic or bicyclic aromatic heterocyclicring include, but are not limited to (numbering starts from theconnection position specified as 1 in terms of priority) pyridinyl(e.g., 2-pyridinyl, 3-pyridinyl or 4-pyridinyl), cinnolinyl, pyrazinyl,2,4-pyrimidinyl, 3,5-pyrimidinyl, 2,4-imidazolyl, imidazopyridinyl,isoxazolyl, oxazolyl, thiazolyl, isothiazolyl, thiadiazolyl (e.g.,1,2,3-thiadiazoly, 1,2,4-thiadiazolyl or 1,3,4-thiadiazolyl),tetrazolyl, thienyl (e.g., thien-2-yl, thien-3-yl), triazinyl,benzothionyl, furyl (or furanyl), benzofuranyl, benzimidazolyl, indolyl,isoindolyl, dihydroindolyl, oxadiazolyl (e.g., 1,2,3-oxadiazolyl,1,2,4-oxadiazolyl or 1,3,4-oxadiazolyl), phthalazinyl, pyrazinyl,pyridazinyl, pyrrolyl, triazolyl (e.g., 1,2,3-triazolyl, 1,2,4-triazolylor 1,3,4-triazolyl), quinolyl, isoquinolyl, pyrazolyl, pyrrolopyridinyl(e.g., 1H-pyrrolo[2,3-b]pyridin-5-yl), pyrazolopyridyl (e.g.,1H-pyrazolo[3,4-b]pyridin-5-yl), benzoxazolyl (e.g.,benzo[d]oxazol-6-yl), pteridinyl, purinyl, 1-oxa-2,3-diazolyl,1-oxa-2,4-diazolyl, 1-oxa-2,5-diazolyl, 1-oxa-3,4-diazolyl,1-thiaza-2,3-diazolyl, 1-thiaza-2,4-diazolyl, 1-thiaza-2,5-diazolyl,1-thiaza-3,4-diazolyl, furazanyl (e.g., furazan-2-yl, furazan-3-yl),benzofurazanyl, benzothiophenyl, benzothiazolyl, benzoxazolyl,quinazolyl, quinoxalinyl, naphthyridinyl, furanopyridinyl,benzothiazolyl (e.g., benzo[d]thiazol-6-yl), indozolyl (e.g.,1H-indazol-5-yl) and 5,6,7,8-tetrahydroisoquinolinyl.

“Heterocyclyl”, “heterocyclic ring” and “heterocyclic” areinterchangeable and refer to non-aromatic heterocyclic groups comprisingone or more heteroatoms selected from nitrogen, oxygen or optionallyoxidized sulfur as ring members (the remaining ring members are carbon),which include monocyclic ring, fused ring, bridged ring and spiro ring,that is, comprise monocyclic heterocyclyl, bridged heterocyclyl, spiroheterocyclyl and fused heterocyclyl.

The term “monocyclic heterocyclyl” refers to a monocyclic group in whichat least one ring member is a heteroatom selected from nitrogen, oxygenor optionally oxidized sulfur. Heterocyclic rings can be saturated orpartially saturated.

Exemplary monocyclic 4-9-membered heterocyclic groups include, but arenot limited to (numbering starts from the connection position specifiedas 1 in terms of priority), pyrrolidin-1-yl, pyrrolidin-2-yl,pyrrolidin-3-yl, imidazolidin-2-yl, imidazolidin-4-yl, pyrazolin-2-yl,pyrazolin-3-yl, piperidin-1-yl, piperidin-2-yl, piperidin-3-yl,piperidin-4-yl, 2,5-piperazinyl, pyranyl, morpholinyl, morpholino,morpholin-2-yl, morpholin-3-yl, oxiranyl, aziridin-1-yl, aziridin-2-yl,aracyclooctan-1-yl, azacyclooctan-2-yl, azacyclooctan-3-yl,azacyclooctan-4-yl, azacyclooctan-5-yl, thiiranyl, azetidin-1-yl,azetidin-2-yl, azetidin-3-yl, oxetanyl, thiacyclobutanyl,1,2-dithiacyclobutanyl, 1,3-dithiacyclobutanyl, dihydropyridinyl,tetrahydropyridinyl, thiomorpholinyl, thioxanyl, piperazinyl,homopiperazinyl, homopiperidyl, azepan-1-yl, azepan-2-yl, azepan-3-yl,azepan-4-yl, oxepanyl, thiepanyl, 1,4-oxathianyl, 1,4-dioxepanyl,1,4-oxapanyl, 1,4-oxazepanyl, 1,4-dithiepanyl, 1,4-azapanyl and1,4-diazepanyl, 1,4-dithianyl, 1,4-azathianyl, oxazepinyl, diazepinyl,thiazepinyl, dihydrothienyl, dihydropyranyl, dihydrofuranyl,tetrahydrofuranyl, tetrahydrothiophenyl, tetrahydropyranyl,tetrahydrothiopyranyl, 1-pyrrolinyl, 2-pyrrolinyl, 3-pyrrolinyl,indolinyl, 2H-pyranyl, 4H-pyranyl, 1,4-dioxolanyl, 1,3-dioxolanyl,pyrazolinyl, pyrazolyl, dithianyl, dithiolanyl, pyrazolidinyl,imidazolinyl, pyrimidinonyl, or 1,1-dioxo-thiomorpholinyl.

The term “spiro heterocyclyl” refers to a 5-20-membered polycyclicheterocyclyl whose rings are connected by a common carbon atom (calledspiro-atom), which comprises one or more heteroatoms selected fromnitrogen, oxygen or optionally oxidized sulfur as ring members, and theremaining ring members are carbon. One or more rings of the spiroheterocyclyl may comprise one or more double bonds, but none of theserings has a fully conjugated n electron system. Preferably, the spiroheterocyclyl is 6-14-membered, more preferably 7-12-membered. Accordingto the number of shared sprio-atoms, the spiro heterocyclyl is dividedinto mono-spiro heterocyclyl, di-spiro heterocyclyl or multi-spiroheterocyclyl, and preferably refers to mono-spiro heterocyclyl ordi-spiro heterocyclyl, and more preferably 4-membered/4-membered,3-membered/5-membered, 4-membered/5-membered, 4-membered/6-membered,5-membered/5-membered, or 5-membered/6-membered mono-spiro heterocyclyl.For example, the spiro heterocyclyl is 7-azaspiro[3.5]nonyl,2-azaspiro[3.3]heptyl, 7-azaspiro[3.5]nonyl or 2-azaspiro[3.5]nonyl.More specifically, the spiro heterocyclyl is 7-azaspiro[3.5]non-2-yl,2-azaspiro[3.3]hept-6-yl, 7-azaspiro[3.5]non-2-yl or2-azaspiro[3.5]non-7-yl.

The term “fused heterocyclyl” refers to 5-20-membered polycyclicheterocyclyl, in which each ring in the system shares an adjacent pairof atoms (carbon and carbon atoms or carbon and nitrogen atoms) withanother ring, which comprises one or more heteroatoms selected fromnitrogen, oxygen or optionally oxidized sulfur as ring members, and theremaining ring members are carbon.

One or more rings of fused heterocyclyl may comprise one or more doublebonds, but none of these rings has a fully conjugated n electron system.Preferably, the fused heterocyclyl is 6-14-membered, and more preferably7-10-membered. According to the number of membered rings, the fusedheterocyclyl is divided into bicyclic, tricyclic, tetracyclic orpolycyclic fused heterocyclyl, preferably bicyclic or tricyclic fusedheterocyclyl, and more preferably 5-membered/5-membered or5-membered/6-membered bicyclic fused heterocyclyl. Representativeexamples of fused heterocyclic rings include, but are not limited to:octahydro cyclopentano[c]pyrrolyl (e.g.,octahydrocyclopentano[c]pyrrol-2-yl), octahydropyrrolo[3,4-c]pyrrolyl,octahydroisoindolyl, isoindolinyl (e.g., isoindolin-2-yl),octahydro-benzo[b][1,4]dioxinyl.

The term “bridged heterocyclyl” refers to 5-14-membered polycyclicheterocyclic alkyl, in which every two rings in the system share twounconnected atoms, comprise one or more heteroatoms selected fromnitrogen, oxygen or optionally oxidized sulfur as ring members, and theremaining ring members are carbon. One or more rings of the bridgedheterocyclyl may comprise one or more double bonds, but none of theserings has a fully conjugated n electron system. Preferably, the bridgedheterocyclyl is 6-14-membered, and more preferably 7-10-membered.According to the number of membered rings, the bridged heterocyclyl isdivided into bicyclic, tricyclic, tetracyclic or polycyclic bridgedheterocyclyl, and preferably refers to bicyclic, tricyclic ortetracyclic bridged heterocyclyl, and more preferably bicyclic ortricyclic bridged heterocyclyl. Representative examples of bridgedheterocyclyl include but are not limited: 2-azabicyclo[2.2.1]heptyl,azabicyclo[3.1.0]hexyl, 2-azabicyclo[2.2.2]octyl and2-azabicyclo[3.3.2]decyl, 3-azabicyclo[3.1.0]hexyl,2-azabicyclo[2.2.1]heptyl, 8-azabicyclo[3.2.1]octyl or2-azabicyclo[4.1.0]heptyl, such as 3-azabicyclo[3.1.0]hex-6-yl,2-azabicyclo[2.2.1]hept-5-yl, 8-azabicyclo[3.2.1]oct-3-yl, or2-azabicyclo[4.1.0]hept-5-yl.

The compounds disclosed herein may comprise asymmetric centers, and thusmay exist as enantiomers. “Enantiomer” refers to two stereoisomers of acompound, which are non-overlapping mirror images of each other. Whenthe compounds disclosed herein have two or more asymmetric centers, theymay additionally exist as diastereomers Enantiomers and diastereomersbelong to a broader category of stereoisomers. It is intended to includeall such possible stereoisomers as substantially pure resolvedenantiomers, racemic mixtures thereof, and diastereomer mixtures. It isintended to include all stereoisomers of the compounds disclosed hereinand/or pharmaceutically acceptable salts thereof. Unless otherwiseexplicitly mentioned, the reference to one isomer applies to anypossible isomer. Whenever the isomer composition is not specified, allpossible isomers are included.

As used herein, the term “substantially pure” means that the targetstereoisomer comprises no more than 35% by weight (such as no more than30%, further such as no more than 25%, even further such as no more than20%) of any other stereoisomer. In some embodiments, the term“substantially pure” means that the target stereoisomer comprises nomore than 10% by weight (for example, no more than 5%, such as no morethan 1%) of any other stereoisomer.

When the compounds disclosed herein comprise olefinic double bonds,unless otherwise specified, such double bonds are intended to include Eand Z geometric isomers.

When the compound disclosed herein comprises disubstituted cyclohexyl orcyclobutyl, the substituents found on the cyclohexyl or cyclobutyl ringcan adopt cis and trans configurations. Cis-configuration means that twosubstituents are found on the upper side of the two substituentpositions on the carbon, while trans-configuration means that they areon the opposite side.

It may be advantageous to separate the reaction products from each otherand/or from the starting materials. The desired products of each step ora series of steps are separated and/or purified (hereinafter separated)to the desired degree of homogeneity by the common techniques in theart. Generally, such separation involves multi-phase extraction,crystallization from solvent or solvent mixture, distillation,sublimation or chromatography. Chromatography can include many methods,including, for example, reverse phase and normal phase; size exclusion;ion exchange; high, medium and low pressure liquid chromatography andapparatus; small-scale analysis: simulated moving bed (SMB) andpreparative thin-layer or thick-layer chromatography, as well assmall-scale thin-layer and fast chromatography technology. Those skilledin the art will apply the technology that is most likely to achieve therequired separation.

“Diastereomer” refers to stereoisomers of a compound with two or morechiral centers, but they are not mirror images of each other. By methodswell known to those skilled in the art, such as chromatography and/orfractional crystallization, diastereomer mixtures can be separated intotheir individual diastereomers based on their physical and chemicaldifferences. Enantiomers can be separated by converting the mixture ofenantiomers into a mixture of diastereomers by reacting with suitableoptically active compounds (e.g., chiral auxiliaries such as chiralalcohol or Mosher's acid chloride), separating the diastereomers andconverting (e.g., hydrolyzing) the respective diastereomers intocorresponding pure enantiomers. Chiral HPLC columns can also be used toseparate enantiomers.

A single stereoisomer (e.g., substantially pure enantiomer) can beobtained by resolving the racemic mixture using a method of formingdiastereomers with optically active resolving agents, for example(Eliel, E. and Wilen, S. Stereochemistry of Organic Compounds. New York:John Wiley & Sons, Inc., 1994; Lochmuller, C. H. et al.,“Chromatographic resolution of enantiomers: Selective review.” J.Chromatogr., 113(3) (1975): pp. 283-302). The racemic mixture of chiralcompounds of the invention can be separated by any suitable method,including: (1) forming ions and diastereomeric salts using chiralcompounds and separating them by fractional crystallization or othermethods; (2) forming diastereomeric compounds using chiral derivatives,separating diastereomers and converting them into pure stereoisomers;and (3) directly separating substantially pure or enriched stereoisomersunder chiral conditions. See: Wainer, Irving W., Ed. DrugStereochemistry. Analytical Methods and Pharmacology. New York: MarcelDekker, Inc., 1993.

“Pharmaceutically acceptable salt” refers to a salt described below,which is suitable for contact with the tissues of human beings and loweranimals within the scope of reliable medical judgment without excessivetoxicity, irritation, allergic reaction, etc., and has a reasonablebenefit/risk ratio. Pharmaceutically acceptable salts can be prepared insitu during the final separation and purification of compounds disclosedherein, or prepared separately by reacting free base functional groupswith suitable organic acids or by reacting acidic groups with suitablebases.

In addition, if the compound disclosed herein is obtained as an acidaddition salt, the free base can be obtained by alkalizing the solutionof the acid salt. Conversely, if the product is a free base, an additionsalt, such as a pharmaceutically acceptable addition salt, can beproduced by dissolving a free base in a suitable organic solvent andtreating the solution with an acid according to the conventionalprocedure for preparing acid addition salts from basic compounds. Thoseskilled in the art will recognize various synthetic methods that can beused to prepare nontoxic pharmaceutically acceptable addition saltswithout undue experimentation.

As defined herein, “pharmaceutically acceptable salts thereof” includesat least one salt of a compound of formula (I) and a salt of astereoisomer of the compound of formula (I), such as a salt of anenantiomer and/or a salt of a diastereomer.

When applied to animals, human, experimental subjects, cells, tissues,organs or biological fluids, the terms “administration”,“administering”, “treating” and “treatment” mean the contact ofexogenous drugs, therapeutic agents, diagnostic agents or compositionswith animals, human, subjects, cells, tissues, organs or biologicalfluids. The treatment of cells includes the contact of reagents withcells, and the contact of reagents with fluids, wherein the fluids arein contact with the cells. The terms “administration”, “administering”,“treating” and “treatment” also mean in vitro and ex vivo treatment ofcells, for example, by using reagents, diagnostic agents, bindingcompounds or by using another cell. The term “subject” herein includesany organism, preferably an animal, more preferably a mammal (e.g., rat,mouse, dog, cat, rabbit) and most preferably a human.

The term “effective amount” or “therapeutically effective amount” refersto the amount of an active ingredient (such as a compound) that issufficient to affect the treatment of a disease or at least one clinicalsymptom of the disease or disorder when the compound is administered toa subject to treat the disease or at least one clinical symptom of thedisease or disorder. The “therapeutically effective amount” may varywith the following factors: the compound, the disease, disorder and/orsymptoms of the disease or disorder, the severity of the disease,disorder and/or symptoms of the disease or disorder, the age of thesubject to be treated and/or the weight of the subject to be treated. Inany given example, the appropriate amount is clear to those skilled inthe art, or can be determined by routine experiments. In someembodiments, a “therapeutically effective amount” is an amount of atleast one compound disclosed herein and/or at least one stereoisomerthereof and/or at least one pharmaceutically acceptable salt thereofthat is effective in “treating” (as defined above) a disease or disorderof a subject. In the case of combination therapy, the “therapeuticallyeffective amount” refers to the total amount of combined objects used toeffectively treat diseases, disorders or symptoms.

Pharmaceutical compositions comprising the compounds disclosed hereincan be administered to subjects in need thereof via oral, inhalation,rectal, parenteral or local administration. For oral administration, thepharmaceutical composition can be conventional solid formulations suchas tablets, powders, granules, capsules, etc., liquid formulations suchas water or oil suspension, or other liquid formulations such as syrup,solution, suspension, etc. For parenteral administration, thepharmaceutical composition can be solution, aqueous solution, oilsuspension concentrate, lyophilized powder, etc. Preferably, theformulation of the pharmaceutical composition is selected from tablets,coated tablets, capsules, suppositories, nasal sprays or injections, andmore preferably tablets or capsules. The pharmaceutical composition canbe administered in a single unit with an accurate dose. In addition, thepharmaceutical composition may also comprise additional activeingredients.

All formulations of the pharmaceutical compositions disclosed herein canbe prepared by conventional methods in the pharmaceutical field. Forexample, the active ingredient can be mixed with one or more excipients,and then prepared into the desired formulation. “Pharmaceuticallyacceptable excipients” refer to conventional pharmaceutical carrierssuitable for the required pharmaceutical formulations, such as diluents,vehicles (such as water, various organic solvents), fillers (such asstarch, sucrose) and binders (such as cellulose derivatives, alginates,gelatin and polyvinylpyrrolidone (PVP)); wetting agents such asglycerin; disintegrants such as agar, calcium carbonate and sodiumbicarbonate; absorption promoters such as quaternary ammonium compounds;surfactants such as cetyl alcohol; absorbing carriers such as kaolin andbentonite; lubricants such as talc, calcium stearate, magnesiumstearate, polyethylene glycol. In addition, the pharmaceuticalcomposition also comprises other pharmaceutically acceptable excipients,such as dispersants, stabilizers, thickeners, complexing agents,buffers, permeation enhancers, polymers, flavoring agents, sweetenersand dyes.

The term “disease” refers to any disease, discomfort, illness, symptomor indication, and is interchangeable with the term “disorder” or“condition”.

Throughout the specification and the following claims, unless thecontext requires otherwise, the terms “comprise” and variations thereofsuch as “comprises” and “comprising” are intended to explain theexistence of subsequent features, but do not exclude the existence oraddition of one or more other functions. As used herein, the term“comprise” can be replaced by the terms “contain”, “include” orsometimes “have”.

Throughout the specification and the following claims, the term “Cn-m”means a range including endpoints, where n and m are integers andrepresent carbon numbers. Examples include C1-8, C1-6, etc.

Unless explicitly defined elsewhere in this document, all othertechnical and scientific terms used herein have the meanings commonlyunderstood by those of ordinary skill in the art to which the inventionbelongs.

General Synthesis

The compounds disclosed herein (including their salts) can be preparedusing known organic synthesis techniques and can be synthesizedaccording to any one of many possible synthesis routes.

The reactions for preparing the compounds disclosed herein can becarried out in suitable solvents, which can be easily selected by thoseskilled in the field of organic synthesis. A suitable solvent may notsubstantially react with the starting materials, intermediates orproducts at the reaction temperature which, for example, may range fromroom temperature to the boiling temperature of the solvent. A givenreaction can be carried out in a solvent or solvent mixture.

Those skilled in the art can easily determine the selection ofappropriate protecting groups.

The reaction can be monitored according to any suitable method known inthe art, such as NMR, UV, HPLC, LC-MS and TLC. Compounds can be purifiedby various methods, including HPLC and normal phase silica gelchromatography.

Chiral HPLC is used to analyze the retention time of different chiralexamples. According to the column, mobile phase and solvent ratio used,the conditions are divided into the following methods.

wherein:

R^(1a), R⁵, L² and R⁶ are as defined for formula (I), m′ is 0, 1, 2 or3, and n′ is 1, 2 or 3.

In scheme I, commercially available ethyl 1H-imidazol-2-carboxylatereacts with 2-O-(4-nitrobenzoyl)hydroxylamine to form compound 2, whichreacts with ethyl chloroformate, and then ring closure reaction iscarried out in the presence of ammonium hydroxide to obtainimidazo[2,1-f][1,2,4]triazin-2,4(1H,3H)-dione 4. After introducing a Bratom using a brominating agent, compound 5 is obtained, and thendiketone is chlorinated to form compound 6. One chlorine atom isreplaced by a protected amine, and the other chlorine atom reacts withR¹ONa to form key intermediate 8, which then reacts with differentaldehydes under alkaline conditions to form formula 9A. The protectinggroup and hydroxyl on the amine are removed to obtain formula 10A. Afterformula 10A is coupled with different acids under alkaline conditions orwith different aldehydes in the presence of reducing agents, thecompound of formula IA is obtained.

wherein R^(1a) and R⁵ are as defined for formula (I), m′ is 0, 1, 2 or3, and n′ is 1, 2 or 3.

In scheme II, this method can also be used to prepare Formula 9A.Imidazo[2,1-f][1,2,4]triazin-2,4(1H,3H)-dione 4 is chlorinated to formcompound 11. One chlorine atom is replaced by a protected amine, and theother chlorine atom reacts with R¹ONa to form key intermediate 13, whichthen reacts with different aldehydes under alkaline conditions to formformula 9A.

wherein R^(1a), R⁵ and R⁶ are as defined for formula (I), m′ is 0, 1, 2or 3, and n′ is 1, 2 or 3.

In scheme III, the key intermediate 8 reacts with different borates inthe coupling reaction with or without metals, and then the protectinggroup on the amine is removed to obtain formula 10A. After formula 10Ais coupled with different acids under alkaline conditions or withdifferent aldehydes in the presence of reducing agents, the compound offormula IA is obtained.

wherein R^(1a), R⁵, L² and R⁶ are as defined for formula (I), m′ is 0,1, 2 or 3, and n′ is 1, 2 or 3.

In scheme IV, the key intermediate 8 reacts with different alkyl aminesand alkyl alcohols in the coupling reaction with or without metals. Theprotecting group on the amine is removed to obtain formula 14. Afterdeprotection and coupling with different acids under alkaline conditionsor with different aldehydes in the presence of reducing agents, thecompound of formula II is obtained.

wherein R^(1a), R⁵, L² and R⁶ are as defined for formula (I), m′ is 0,1, 2 or 3, and n′ is 1, 2 or 3.

In scheme V, the key intermediate 8 or 13 reacts with DMF ormorpholin-4-formaldehyde under alkaline conditions to form aldehyde 15,which reacts with different amines in the presence of reducing agent toform formula 10B. After deprotection and coupling with different acidsunder alkaline conditions or with different aldehydes in the presence ofreducing agents, the compound of formula IB is obtained.

EXAMPLES

The following examples are intended to be exemplary only and should notbe considered as limiting in any way. Unless otherwise stated, theexperimental methods in the following examples are conventional methods.Unless otherwise stated, reagents and materials are commerciallyavailable. All solvents and chemicals used are analytical or chemicallypure. Solvents should be distilled again before use. Anhydrous solventsare prepared according to standard methods or reference methods. Silicagel (100-200 mesh) for column chromatography and silica gel (GF254) forthin layer chromatography (TLC) can be obtained commercially fromTsingdao Haiyang Chemical Co., Ltd. or Yantai Chemical Co., Ltd inChina; unless otherwise stated, all of them are eluted with petroleumether (60-90° C.)/ethyl acetate (v/v) and developed with iodine orphosphomolybdic acid solution in ethanol. Unless otherwise stated, allextraction solvents are dried over anhydrous Na₂SO₄. ¹H NMR spectrum isrecorded on Bruck-400 NMR spectrometer with TMS (tetramethylsilane) asinternal standard. LC/MS data are recorded by using Agilent1100 highperformance liquid chromatography-ion trap mass spectrometer (LC-MSDTrap) equipped with diode array detector (DAD) for detection at 214 nmand 254 nm and ion trap (ESI source). The names of all compounds exceptreagents are generated by ChemDraw®.

In the following examples, the following abbreviations are used;

-   AcOH Acetic acid-   Aq. Aqueous-   BINAP 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl-   Brine Saturated aqueous sodium chloride solution-   Bn Benzyl-   BnBr Benzyl bromide-   BPO Benzoyl peroxide-   BSA N,O-bis(trimethylsilyl)acetamide-   CH₂Cl₂ or DCM Dichloromethane-   DIAD Diisopropyl azodiformate-   DMF N,N-dimethylformamide-   Dppf 1,1′-bis(diphenylphosphino)ferrocene-   DBU 1,8-diazabicyclo[5.4.0]undec-7-ene-   DIEA or DIPEA N,N-diisopropylethylamine-   DMAP 4-N,N-dimethylaminopyridine-   DMF N,N-dimethylformamide-   DMSO Dimethylsulfoxide-   EtOAc or EA Ethyl acetate-   EtOH Ethanol-   Et₂O or ether Diethyl ether-   g Gram-   h or hr hour-   HATU O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium    hexafluorophosphate-   Hex hexane-   HCl Hydrochloric acid-   HMDS Hexamethyldisilazane-   HPLC high performance liquid chromatography-   IBX 2-iodoxybenzoic acid-   IPA Isopropyl alcohol-   i-PrOH Isopropanol-   LCMS Liquid chromatography-mass spectrometry-   mg Milligram-   mL Milliliter-   mmol Millimole-   MeCN Acetonitrile-   MeOH Methanol-   Min Minute-   ms or MS Mass spectrometry-   MTBE Methyl tert-butyl ether-   Na₂SO₄ Sodium sulfate-   NBS N-bromosuccinimide-   NMP N-methylpyrrolidone-   PE Petroleum ether-   PMB (4-methoxyphenyl)methylamine-   prep Preparation-   Rt or rt Room temperature-   sat. Saturated-   TBAF Tetrabutyl ammonium fluoride-   TBSCl Tert-butyl dimethyl silyl chloride-   t-BuOK Potassium tert-butoxide-   TFA Trifluoroacetic acid-   THF Tetrahydrofuran-   TLC Thin-layer chromatography-   μL Microliter

Synthesis of Intermediate I7-bromo-2-butoxy-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Ethyl 1-amino-1H-imidazol-2-carboxylate hydrochloride

t-BuOK (1 M in THF, 440 ml, 0.44 mol) was added to a stirred solution ofethyl 1H-imidazol-2-carboxylate (56 g, 0.4 mol) in NMP (1.2 L) at 20-30°C. The mixture was stirred for 0.5 h. A solution ofO-(4-nitrobenzoyl)hydroxylamine (80.08 g, 0.44 mol) in NMP (0.4 L) wasadded dropwise at a temperature below 30° C. The solution was stirred atroom temperature for 2 h and diluted with MTBE (500 ml). HCl (4 M in EA,100 ml) was added to quench the reaction. Diatomite (20 g) was added tothe above mixture which was then stirred for 0.5 h. The mixture wasfiltered. The filtrate was diluted with MTBE (2 L) and HCl (4 M in EA,200 ml) was added dropwise. The suspension was stirred for 0.5 h andfiltered. The filter cake was washed with MTBE and dried in an oven toobtain the product (70 g, 91%). MS: We 156 (M+1)⁺.

Step B: Mixture of ethyl1-((ethoxycarbonyl)amino)-1H-imidazol-2-carboxylate and ethyl1-(bis(ethoxycarbonyl)amino)-1H-imidazol-2-carboxylate (1:1)

To a stirred solution of ethyl 1-amino-1H-imidazol-2-carboxylatehydrochloride (80 g, 0.42 mol) in THF (900 ml) and H₂O (900 ml), NaHCO₃(178.9 g, 2.1 mol) was added in several batches. Ethyl chloroformate(98.55 g, 0.9 mol) was added dropwise at a temperature below 30° C. Themixture was stirred at room temperature for 4 h, diluted with EA (1 L)and then separated. The aqueous layer was extracted with EA (800 ml).The collected organic layer was washed with brine, dried over Na₂SO₄,filtered and concentrated to obtain a crude product (113 g) as yellowoil, which can be directly used in the next step without furtherpurification. MS: M/e 228 (M+1)⁺ & M/e 300 (M+1)⁺

Step C: Imidazo[2,1-f][1,2,4]triazin-2,4(1H,3H)-dione

A mixture of ethyl 1-((ethoxycarbonyl)amino)-1H-imidazol-2-carboxylateand ethyl 1-(bis(ethoxycarbonyl)amino)-1H-imidazol-2-carboxylate (110 g)in ammonium hydroxide (400 ml, 3.6 V) and IPA (2(0) ml, 1.8 V) was addedinto a sealed tube. The mixture was stirred at 120° C. overnight. Aftercooling, the mixture was filtered. The filter cake was rinsed with MeOH.The filtrate was concentrated under reduced pressure. The resultingresidue was pulped in MeOH, filtered and rinsed with MeOH. The obtainedfilter cake was mixed with the previous filter cake and dried in an ovento obtain the product (56 g) as a white solid. MS: M/e 153 (M+1)⁺.

Step D: 7-bromoimidazo[2,1-f][1,2,4]triazin-2,4-(1H,3H)-dione

To a solution of imidazo[2,1-f][1,2,4]triazin-2,4(1H,3H)-dione (30 g,0.20 mol) in H₂O (1.2 L). NBS (24.6 g, 0.14 mol) was added in severalbatches at a temperature below 25° C. The mixture was stirred at roomtemperature for 1 h, and then filtered. The filtrate was concentrated toremove the solvent. The resulting residue was mixed with the previousfilter cake and pulped in MeOH (20 V) and then in MeOH:H₂O (1:1, 20 V)to obtain the product (30.4 g, 94%) as a white solid. MS: M/e 231(M+1)⁺.

Step E: 7-bromo-2,4-dichloroimidazo[2,1-f][1,2,4]triazine

To a 350 ml sealed tube,7-bromoimidazo[2,1-f][1,2,4]triazin-2,4(1H,3H)-dione (10 g, 43 mmol),triethylamine hydrochloride (12 g, 88 mmol) and POCl₃ (100 ml) wereadded. The mixture was stirred at 120° C. overnight, and thenconcentrated to remove POCl₃. The residue was diluted with EA (200 ml),and saturated NaHCO₃ (aqueous solution) was added dropwise at atemperature below 20° C. until the pH was higher than 7. The solutionwas separated. The organic layer was washed with H₂O, dried over Na₂SO₄,filtered and concentrated. The resulting residue was purified by columnchromatography eluted with 0-20% EA in PE to obtain the product (8.5 g,73%) as a white solid. MS: M/e 267 (M+1)⁺.

Step F:7-bromo-2-chloro-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine

TEA (22.6 g, 0.22 mol) was added dropwise to a stirred solution of7-bromo-2,4-dichloroimidazo[2,1-f][1,2,4]triazine (30 g, 0.11 mol) inTHF (500 ml). The mixture was stirred at room temperature for 10 min. Asolution of bis(4-methoxybenzyl)amine (31.6 g, 0.12 mol) in THF (80 ml)was added dropwise to the above solution. The mixture was stirred atroom temperature for 2 h. The solution was quenched with H₂O (300 ml)and then extracted with EA (200 ml×2). The organic layer was washed withbrine, dried over Na₂SO₄, filtered and concentrated. The resultingresidue was pulped in PE (300 ml) and filtered to obtain the product(41.4 g, 76%) as a white solid. MS: M/e 488 (M+1)⁺.

Step G:7-bromo-2-butoxy-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of7-bromo-2-chloro-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(35 g, 71.6 mmol) and n-BuONa/n-BuOH (20%, 200 ml) was stirred at 80° C.under N₂ for 1 h. The solution was quenched with H₂O (200 ml). Theaqueous solution was extracted with EA (150 ml×2). The collected organiclayer was washed with brine, dried over Na₂SO₄, filtered andconcentrated. The resulting residue was purified by columnchromatography eluted with 0-20% EA in PE to obtain the product (33 g,88%) as colorless oil, which would be solidified after several hours.MS: M/e 526 (M+1)⁺.

Synthesis of Intermediate II2-chloro-N,N-bis(2,4-dimethoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine

DIPEA (25.5 g, 0.20 mmol) was added to a mixture ofimidazo[2,1-f][1,2,4]triazin-2,4(1H,3H)-dione (10 g, 65.8 mmol), POCl₃(50 g, 0.20 mmol) and toluene (60 mL) within 30 min at 60° C. At thistime, heat release was noticed, and the temperature rose to 90° C. (Thesolid was gradually dissolved). After the addition was completed, thereaction was warmed to 100° C. (internal temperature was about 95° C.)and stirred overnight. The reaction was then cooled to room temperature.The mixture was concentrated under reduced pressure. The residue wasdissolved in THF (100 mL), and DIPEA (25.5 g, 0.20 mmol) was then addeddropwise to the mixture. The mixture was added to a solution ofbis(2,4-dimethoxybenzyl)amine (31.3 g, 0.10 mol), K₂CO₃ (18 g, 1.32mol), THF (260 mL) and water (260 mL) at 0° C. within 1 h. After theaddition was completed, the mixture was extracted with EA (300 mL×3).The combined organic phases were washed with brine, dried over Na₂SO₄and concentrated under reduced pressure. The residue was dissolved in EA(400 mL), and the mixture was stirred under reflux for 1 h and filteredat this temperature. The filtrate was concentrated under reducedpressure. EA was exchanged for MeOH, and the mixture was stirred at roomtemperature overnight. The mixture was filtered and the solid(off-white) was collected. The product was directly used in the nextstep (20 g, HPLC: 98.87%, yield: 54.4%).

Compound B1:2-butoxy-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-butoxyimidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of7-bromo-2-butoxy-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(200 mg, 0.38 mmol) in THF (8 mL), a solution of n-BuLi (0.4 mL, 0.6mmol) was added dropwise at a temperature of −75° C. to −65° C. One hourlater, a solution of tert-butyl 4-formylpiperidin-1-carboxylate (120 mg,0.57 mmol) in THE (1 mL) was added dropwise. The resulting mixture wasstirred at −70° C. for 1 h and then warmed to room temperature to reactfor 3 h. The reaction was quenched with a saturated NH₄Cl solution,extracted with EtOAc (60 mL), washed with brine, dried over Na₂SO₄,filtered and concentrated. The residue was purified by preparative TLCto obtain the target compound (210 mg, crude). MS: M/e 661 (M+1)⁺.

Step B:2-butoxy-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (2 mL) was added to a mixture of the product of step B (210 mg,crude) in TFA (6 mL). The reaction was heated at 85° C. for 72 h. Themixture was concentrated to dryness, and the residue was purified bypreparative HPLC to obtain the product (20 mg, 17% for two steps). ¹HNMR(400 MHz, DMSO-d₆) δ 8.49 (s, 1H), 8.16 (s, 1H), 8.10 (s, 1H), 7.37 (d,J=2.0 Hz, 1H), 4.22 (t, J=6.8 Hz, 2H), 3.24 (d, J=12.0 Hz, 2H),2.95-2.72 (m, 4H), 2.11-1.89 (m, 1H), 1.81-1.64 (m, 4H), 1.52-1.26 (m,4H), 0.94 (t, J=7.6 Hz, 3H) ppm. MS: Me 305 (M+1)⁺.

Compound B2:2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A;N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

NaH (1.27 g, 31.75 mmol, 60%) was added to a solution of pentan-2-ol(2.8 g, 31.82 mmol) in THF (50 mL) at 0° C. under N2. After the mixturewas stirred at 25° C. for 0.5 h,2-chloro-N,N-bis(2,4-dimethoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(5 g, 10.64 mmol) was added. The reaction mixture was stirred at 70° C.for 16 h. Upon completion of the reaction, the reaction mixture wasquenched with water (50 mL) and extracted with EtOAc (3×50 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (25%) inpetroleum ether to obtain the title compound (4.8 g, 87%). ¹H NMR (400MHz, DMSO-d₆) δ 7.93 (s, 1H), 7.50 (s, 1H), 7.04-6.96 (m, 2H), 6.60-6.52(m, 2H), 6.45 (m, 2H), 5.64 (m, 2H), 4.94-4.84 (m, 1H), 4.72 (m, 2H),3.73 (t, J=9.2 Hz, 12H), 1.68-1.41 (m, 2H), 1.37-1.25 (m, 2H), 1.23 (t,J=7.2 Hz, 3H), 0.84 (t, J=7.2 Hz, 3H) ppm. MS: Me 458 (M+1)⁺.

Step B: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

At −78° C. under N₂ atmosphere, n-BuLi (1.6 M, 2.85 mL, 4.6 mmol) wasadded to a stirred solution ofN,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(1.17 g, 2.3 mmol) in THF (10 mL). The mixture was stirred at −78° C.for 1 h. Then, a solution of tert-butyl 4-formylpiperidin-1-carboxylate(0.97 g, 4.6 mmol) in THF (10 mL) was added to the system at −78° C. Thereaction was warmed to room temperature and stirred overnight. Thereaction was quenched with a saturated aqueous solution of NH₄Cl at roomtemperature. The mixture was extracted with EA (20 mL×3). The combinedorganic phases were washed with brine, dried over Na₂SO₄ andconcentrated under reduced pressure. The residue was purified bycombiflash to obtain the title compound (1.2 g, yield: 71.0%). MS: M/e735 (M+1)⁺.

Step C:(4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(piperidin-4-yl)methanol

A mixture of the product of step B (1.2 g, 1.6 mmol) in TFA/H₂O (9:1, 12mL) was stirred at 30° C. overnight. The reaction was cooled to roomtemperature and concentrated under reduced pressure. The mixture wasconcentrated and 20 mL of H₂O was added. The mixture was stirred at roomtemperature for 30 min and then filtered. The filtrate was extractedwith DCM (20 mL×3) to remove impurities. The aqueous layer was alkalizedto pH=12 with an aqueous NaOH (2 M) solution and extracted with DCM/IPA(8:2, 20 mL×3). The combined extracts were washed with brine (20 mL),dried over Na₂SO₄ and concentrated to obtain the title product (350 mg,yield: 64.1%). MS: M/e 335 (M+1)⁺.

Step D:2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of the product of step C (350 mg, 1.05 mmol), TFA (2.5 mL) andEt₃SiH (4 mL) was stirred at 60° C. overnight. As detected by LC_Ms,there was no residual starting materials. TFA (1 mL) was added to themixture, and the resulting mixture was stirred at 60° C. overnight. Thereaction was concentrated under reduced pressure. The residue wasdissolved in water (15 mL) and extracted with DCM (25 mL×3). The organicphase was discarded. The inorganic phase was alkalinized with an aqueousNaOH (2 M) solution to pH=12. A white solid precipitated out of thesystem. The mixture was extracted with DCM/iPrOH (8:2, 20 mL×2). Thecombined organic phases were washed with a 20% aqueous NaCl solution,dried over Na₂SO₄ and concentrated. The residue was purified bycombiflash to obtain the title compound (90 mg, yield: 27.0%). ¹H NMR(400 MHz, DMSO-d6) δ 8.21-7.80 (m, 2H), 7.27 (s, 1H), 5.06-4.89 (m, 1H),2.98-2.80 (m, 2H), 2.69 (d, J=6.6 Hz, 2H), 2.38 (t, J=12 Hz, 2H),1.86-1.61 (m, 2H), 1.58-1.47 (m, 3H), 1.43-1.33 (m, 2H), 1.26 (t, J=6.0Hz, 3H), 1.08 (dd, J=20.8, 12 Hz, 2H), 0.90 (t, J=7.2 Hz, 3H) ppm. MS:M/e 319 (M+1)⁺. MS: M/e 319 (M+1)⁺.

Compound B3:2-butoxy-7(2-(piperidin-4-yl)ethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl4-(2-(4-(bis(4-methoxybenzyl)amino)-2-butoxyimidazo[2,1-f][1,2,4]triazin-7-yl)-2-hydroxyethyl)piperidin-1-carboxylate

At −78° C. under N₂ atmosphere, n-BuLi (1.6 M, 0.57 mL) was added to astirred solution of7-bromo-2-butoxy-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(150 mg, 0.29 mmol) in THE (10 mL). The mixture was stirred at −78° C.for 1 h. Then, a solution of ten-butyl4-(2-oxoethyl)piperidin-1-carboxylate (92 mg, 0.41 mmol) in THF (0.5 mL)was added to the system at −78° C. The reaction was warmed to roomtemperature and stirred overnight. The reaction was quenched with asaturated aqueous NH₄Cl solution at room temperature. The mixture wasextracted with EA (20 mL×3). The combined organic phases were washedwith brine, dried over Na₂SO₄ and concentrated under reduced pressure.The residue was purified by combiflash to obtain the title compound (150mg, yield: 76.7%). MS: M/e 675 (M+1)⁺.

Step B:2-butoxy-7-(2-(piperidin-4-yl)ethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

CF₃COOH (2 mL) was added to a stirred solution of the product of step A(150 mg, 0.22 mmol) in Et₃SiH (4 mL) at room temperature. The mixturewas stirred at 80° C. for 1 h. The reaction was cooled to roomtemperature and concentrated under reduced pressure. The residue wasdissolved in CF₃COOH (4 mL), and the mixture was stirred at 80° C.overnight. The reaction was cooled to room temperature. The mixture wasconcentrated under reduced pressure. The residue was purified bypreparative HPLC to obtain the title compound (15 mg, yield: 21.4%). ¹HNMR (400 MHz, DMSO-d6) δ 8.15-7.90 (m, 2H), 7.29 (s, 1H), 4.20 (t, J=6.4Hz, 2H), 2.94 (d, J=12.0 Hz, 2H), 2.78 (t, J=7.6 Hz, 2H), 2.44 (t,J=11.6 Hz, 2H), 1.77-1.52 (m, 6H), 1.50-1.35 (m, 2H), 1.35-1.24 (m, 1H),1.13-0.99 (m, 2H), 0.93 (t, J=7.2 Hz, 3H) ppm. MS: M/e 319 (M+1)⁺.

Compound B4:N2-butyl-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-2,4-diamine

Step A:7-bromo-N2-butyl-N4,N4-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-2,4-diamine

A mixture of7-bromo-2-chloro-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(244 mg, 0.5 mmol), butyl-1-amine (365 mg, 5 mmol) and DIPEA (645 mg, 5mmol) in NMP (3 mL) was stirred in a sealed tube at 220° C. for 6 h. Themixture was poured into H₂O (10 mL) and extracted with EtOAc (10 mL×3).The combined organic layers were washed with brine, dried over Na₂SO₄,concentrated and purified by column chromatography (petroleumether/EtOAc=20:1-5:1) to obtain the target compound (220 mg, 83.8%). MS:M/e 525/527 (M+1)⁺.

Step B: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-(butylamino)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

At −78° C. under N₂ atmosphere, n-BuLi (1.6 M, 0.54 mL, 0.86 mmol) wasadded to a stirred solution of7-bromo-N²-butyl-N⁴,N⁴-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-2,4-diamine(150 mg, 0.29 mmol) in THF (5 mL). The mixture was stirred at −78° C.for 1 h. Then, a solution of tert-butyl 4-formylpiperidin-1-carboxylate(91 mg, 0.39 mmol) in THF (0.5 mL) was added to the system at −78° C.The reaction was warmed to room temperature and stirred overnight. Thereaction was quenched with a saturated aqueous NH₄Cl solution at roomtemperature. The mixture was extracted with EA (20 mL×3). The combinedorganic phases were washed with brine, dried over Na₂SO₄ andconcentrated under reduced pressure. The residue was purified bycombiflash to obtain the title compound (110 mg, yield: 58.3%) as yellowoil. MS: M/e 660 (M+1)⁺.

Step C:N²-butyl-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-2,4-diamine

CF₃COOH (2 mL) was added to a stirred solution of the product of step B(110 mg, 0.17 mmol) in Et₃SiH (4 mL) at room temperature. The mixturewas stirred at 80° C. for 1 h. The reaction was cooled to roomtemperature and concentrated under reduced pressure. The residue wasdissolved in CF₃COOH (4 mL), and the mixture was stirred at 80° C.overnight. The reaction was cooled to room temperature. The mixture wasconcentrated under reduced pressure. The residue was purified bypreparative HPLC to obtain the title compound (15 mg, yield, 50.7%). ¹HNMR (400 MHz, DMSO-d6) δ 7.46 (br.s, 2H), 7.11 (s, 1H), 6.36-5.96 (m,1H), 3.22-3.08 (m, 2H), 3.00-2.86 (m, 2H), 2.74-2.59 (m, 2H), 2.48-2.38(m, 2H), 1.80 (br.s, 1H), 1.60-1.45 (m, 4H), 1.41-1.29 (m, 2H),1.18-1.00 (m, 2H), 0.90 (t, J=7.2 Hz, 3H) ppm. MS: M/e 304 (M+1)⁺.

Compound B5:N²-(pent-2-yl)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-2,4-diamine

Step A:7-bromo-N⁴,N⁴-bis(4-methoxybenzyl)-N2-(pent-2-yl)imidazo[2,1-f][1,2,4]triazin-2,4-diamine

To a stirred solution of7-bromo-2-chloro-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(1 g, 2.05 mmol) in NMP (10 mL), pentyl-2-amine (1 g, 11.5 mmol) andDIEA (400 mg, 3.1 mmol) were added. The reaction mixture was sealed andstirred at 220° C. for 6 h. The mixture was cooled to room temperature,H₂O (20 mL) was added and the mixture was extracted with EtOAc (10ml×3). The combined organic phases were washed with brine, dried overNa₂SO₄ and concentrated under vacuum. The crude product was purified bycolumn chromatography to obtain the product (250 mg, 22.7%) as a whitesolid. MS: M/e 539 (M+1)⁺.

Step B: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-(pent-2-ylamino)imidazo[2,1-][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

At −78° C. under N₂ atmosphere, n-BuLi (1.6 M, 0.56 mL, 0.9 mmol) wasadded to a stirred solution of7-bromo-2-butoxy-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(161 mg, 0.29 mmol) in THF (2 mL). The mixture was stirred at −78° C.for 1 h. Then, a solution of tert-butyl4-(2-oxoethyl)piperidin-1-carboxylate (76.5 mg, 0.36 mmol) in THF (0.3mL) was added to the system at −78° C. The reaction was warmed to roomtemperature and stirred overnight. The reaction was quenched with asaturated aqueous NH₄Cl solution at room temperature. The mixture wasextracted with EA (20 mL×3). The combined organic phases were washedwith brine, dried over Na₂SO₄ and concentrated under reduced pressure.The residue was purified by combiflash to obtain the title compound (80mg, yield: 39.8%) as yellow oil. MS: M/e 674 (M+1)⁺.

Step C:N²-(pent-2-yl)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-2,4-diamine

CF₃COOH (2 mL) was added to a stirred solution of the product of step B(80 mg, 0.12 mmol) in Et₃SiH (4 mL) at room temperature. The mixture wasstirred at 80° C. for 1 h. The reaction was cooled to room temperatureand concentrated under reduced pressure. The residue was dissolved inCF₃COOH (4 mL), and the mixture was stirred at 80° C. overnight. Thereaction was cooled to room temperature. The mixture was concentratedunder reduced pressure. The residue was purified by preparative HPLC toobtain the title compound (9 mg, yield: 23.9%). ¹H NMR (400 MHz,DMSO-d6) δ 7.43 (br.s, 2H), 7.10 (s, 1H), 5.94 (d, J=8.0 Hz, 1H),3.91-3.61 (m, 1H), 3.03-2.82 (m, 2H), 2.74-2.58 (m, 2H), 2.46-2.31 (m,2H), 1.92-1.73 (m, 1H), 1.65-1.48 (m, 3H), 1.42-1.28 (m, 3H), 1.14-1.01(m, 5H), 0.99-0.81 (m, 3H) ppm. MS: M/e 318 (M+1)⁺.

Compound B6:(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

NaH (60% in mineral oil, 1.07 g, 26.7 mmol) was slowly added to asolution of (S)-pentan-2-ol (2.35 g, 26.7 mmol) in THF (50 mL) at roomtemperature. The mixture was stirred at room temperature for 1 h,2-chloro-N,N-bis(2,4-dimethoxybenzyl)imidazo[2,1-f][1,2,4,]triazin-4-amine(5 g, 10.7 mmol) was added, and the resulting mixture was stirred at 60°C. overnight. The reaction was cooled to room temperature. The mixturewas quenched with 80 mL of water and extracted with EA (60 mL×2). Thecombined organic phases were washed with brine, dried over Na₂SO₄ andconcentrated. The residue was purified by combiflash to obtain the titleproduct (4.5 g, yield: 81.1%) as a gel. MS: M/e 522 (M+1)⁺.

Step B: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

At −78° C. under N₂ atmosphere, n-BuLi (1.6 M, 3.8 mL, 6 mmol) was addedto a stirred solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(1.56 g, 3 mmol) in THF (10 mL). The mixture was stirred at −78° C. for1 h. Then, a solution of tert-butyl 4-formylpiperidin-1-carboxylate (1.3g, 6 mmol) in THF (1 mL) was added to the system at −78° C. The reactionwas kept at room temperature and stirred overnight. The reaction wasquenched with a saturated aqueous NH₄Cl solution at room temperature.The mixture was extracted with EA (20 mL×3). The combined organic phaseswere washed with brine, dried over Na₂SO₄ and concentrated under reducedpressure. The residue was purified by combiflash to obtain the titlecompound (1.6 g, yield: 72.7%). MS: M/e 735 (M+1)⁺.

Step C:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(piperidin-4-yl)methanol

Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate(1.4 g, 1.9 mmol) in TFA/H₂O (9:1, 20 mL) was stirred at roomtemperature for 65 h. The reaction was concentrated under reducedpressure, 20 mL of H₂O was added. The mixture was stirred at roomtemperature for 30 min and then filtered. The filtrate was extractedwith DCM (20 mL×3) to remove impurities. The aqueous layer was alkalizedwith an aqueous NaOH (4 M) solution to pH>10, and extracted with DCM/IPA(5:1, 20 mL×5). The combined extracts were washed with brine (50 mL×3),dried over Na₂SO₄ and concentrated to obtain the title product (460 mg,yield: 72%). MS: M/e 335 (M+1)⁺.

Step D:(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(piperidin-4-yl)methanol(460 mg, 1.37 mmol), TFA (10 mL) and Et₃SiH (10 mL) were stirred at 60°C. overnight. As detected by LC_MS, the starting materials disappeared.Et₃SiH (5 mL) was added to the mixture and the mixture was stirred at60° C. overnight. The reaction was concentrated under reduced pressure.The residue was dissolved in HCl (4 M, 2 mL) and extracted with DCM (5mL×3). The organic phase was discarded. The inorganic phase wasalkalized to pH=12 with an aqueous NaOH (4 M) solution. A white solidprecipitated out of the system. The mixture was extracted with DCM/iPrOH(5:1, 10 mL×5). The combined organic phases were washed with brine (20mL×2), dried over Na₂SO₄ and concentrated. The residue was purified bycolumn chromatography to obtain the title compound (320 mg, yield: 72%).¹H NMR (400 MHz, DMSO-d6) δ 8.04 (br.s, 1H), 7.94 (br.s, 1H), 7.27 (s,1H), 5.03-4.89 (m, 1H), 2.87 (d, J=12.0 Hz, 2H), 2.68 (d, J=6.8 Hz, 2H),2.36 (t, J=12.0 Hz, 2H), 1.84-1.61 (m, 2H), 1.59-1.44 (m, 3H), 1.44-1.32(m, 2H), 1.28 (d, J=6.2 Hz, 3H), 1.14-0.99 (m, 2H), 0.91 (t, J=7.2 Hz,3H) ppm. MS: M/e 319 (M+1)⁺.

Compound B7:(R)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Compound B7 was obtained as follows: compound B2 was subjected to chiralresolution to obtain two chiral compounds B6 and B7.

Conditions of preparative HPLC

Column CHIRALPAK ID Column size 2 cm × 25 cm, 5 μm Injection 0.3 mlMobile phase [(Hexane:DCM = 3:1)(0.1% isopropanolamine)(IP Amine)]:IPA =90:10 Flow rate 20 mL/min Wavelength UV 220 nm Temperature 25° C. Samplesolution 23 mg/ml in EtOH:DCM = l:1 Preparative HPLC instrumentPreparative HPLC-Gilson

Compound B7:(R)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

¹H NMR (400 MHz DMSO-d6) δ 8.14-7.86 (m, 2H), 7.27 (s, 1H), 5.06-4.88(m, 1H), 2.98-2.81 (m, 2H), 2.69 (d, J=6.6 Hz, 2H), 2.38 (t, J=11.6 Hz,2H), 1.85-1.61 (m, 2H), 1.58-1.45 (m, 3H), 1.44-1.32 (m, 2H), 1.28 (d,J=6.0 Hz, 3H), 1.08 (dd, J=21.6, 11.6 Hz, 2H), 0.90 (t, J=7.2 Hz, 3H)ppm. MS: M/e 319 (M+1)⁺.

Compound B8:7-((4-methylpiperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Benzyl 4-formyl-4-methylpiperidin-1-carboxylate

To a stirred mixture of benzyl 4-formylpiperidin-1-carboxylate (2 g,8.09 mmol) in DCM (20 ml), t-BuOK (1.2 g, 10.7 mmol) and CH₃I (1.55 ml,24.9 mmol) were added. Thereafter, the reaction mixture was stirred atroom temperature overnight. The reaction mixture was poured into H₂O andextracted with EtOAc (15 mL×3). The combined organic phases were washedwith brine, dried over Na₂SO₄ and concentrated under vacuum. The crudeproduct was purified by column chromatography to obtain the titleproduct (8(0) mg, 38%) ¹H NMR (400 MHz, CDCl₃-d6) δ 9.45 (t, J=5.4 Hz,1H), 7.40-7.28 (m, 5H), 5.13 (dd, J=5.8, 1.0 Hz, 2H), 3.84-3.68 (m, 2H),3.26-3.09 (m, 2H), 1.93 (d, J=13.2 Hz, 2H), 1.42 (s, 2H), 1.08 (d, J=2.3Hz, 3H) ppm. MS: Me 262 (M+1)⁺.

Step B: Benzyl4-((4-(bis(4-methoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-4-methylpiperidin-1-carboxylate

To a stirred solution ofN,N-bis(4-methoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(200 mg, 0.43 mmol) in THF (8 mL) cooled to −78° C. under nitrogenatmosphere, n-BuLi (1.6 M in hexane, 0.86 mmol, 0.54 mL) was addeddropwise. After the mixture was stirred for 30 min, a solution of benzyl4-formyl-4-methylpiperidin-1-carboxylate (226 mg, 0.86 mmol) in THF (2mL) was slowly added. The reaction mixture was slowly warmed to roomtemperature and stirred overnight. The reaction mixture was poured intoa saturated ammonium chloride solution and extracted with EtOAc (15mL×3). The combined organic phases were washed with brine, dried overNa₂SO₄ and concentrated under vacuum. The crude product was purified bycolumn chromatography to obtain the title product (120 mg, 38.7%). MS:M/e 723 (M+1)⁺.

Step C:7-((4-methylpiperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (5 ml) was added to a stirred mixture of benzyl4-((4-(bis(4-methoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-4-methylpiperidin-1-carboxylate(120 mg, 0.166 mmol) in TFA (5 ml). Thereafter, the reaction mixture wasstirred at 80° C. for 2 h. The mixture was cooled to room temperatureand concentrated under vacuum. TFA (10 ml) was added to the residue andthe mixture was stirred at 80° C. overnight. The reaction mixture wascooled to room temperature and concentrated under vacuum. The residuewas purified by preparative HPLC to obtain the target compound (10 mg,22.4%). ¹H NMR (400 MHz, DMSO-d6) δ 8.42 (s, 1H), 8.30 (s, 1H), 8.13 (s,1H), 8.04 (s, 1H), 7.36 (s, 1H), 4.99 (s, 1H), 3.17 (s, 2H), 3.03 (s,2H), 2.86 (s, 2H), 1.73-1.51 (m, 4H), 1.43 (m, 4H), 1.28 (d, J=4.7 Hz,3H), 0.98 (s, 3H), 0.90 (br.s, 3H) ppm. MS: M/e 333 (M+1)⁺.

Compound B9:2-(pent-2-yloxy)-7-(piperazin-1-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

NaH (1.27 g, 31.75 mmol, 60%) was added to a solution of pentan-2-ol(2.8 g, 31.82 mmol) in THF (50 mL) at 0° C. under N2. After the mixturewas stirred at 25° C. for 0.5 h,2-chloro-N,N-bis(2,4-dimethoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(5 g, 10.64 mmol) was added. The reaction mixture was stirred at 70° C.for 16 h. After completion of the reaction, the reaction mixture wasquenched with water (50 mL) and extracted with EtOAc (3×50 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (25%) inpetroleum ether to obtain the title compound (4.8 g, 87%). ¹H NMR (400MHz, DMSO-d₆) δ 7.93 (s, 1H), 7.50 (s, 1H), 7.04-6.96 (m, 2H), 6.60-6.52(m, 2H), 6.45 (m, 2H), 5.64 (m, 2H), 4.94-4.84 (m, 1H), 4.72 (m, 2H),3.73 (t, J=9.2 Hz, 12H), 1.68-1.41 (m, 2H), 1.37-1.25 (m, 2H), 1.23 (t,J=7.2 Hz, 3H), 0.84 (t, J=7.2 Hz, 3H) ppm. MS: M/e 458 (M+1)⁺.

Step B:4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-formaldehyde

To a solution ofN,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(3 g, 5.76 mmol) in THF (100 mL), n-BuLi (7.2 mL, 11.52 mmol) was addedat −78° C. under N₂. After the mixture was stirred at −78° C. for 1 h,DMF (1.7 g, 23.29 mmol) was added. The reaction mixture was warmed to25° C. and stirred for 3 h. After completion of the reaction, thereaction mixture was quenched with an aqueous NH₄Cl solution (80 mL) andextracted with EtOAc (3×100 mL). The combined organic layers were driedover Na₂SO₄ and concentrated under vacuum to obtain a residue. Theresidue was purified by column chromatography on silica gel eluted withethyl acetate (25%) in petroleum ether to obtain the title compound (1.8g, 57%). ¹H NMR (300 MHz, DMSO-d₆) δ 10.17 (s, 1H), 8.14 (s, 1H), 7.04(d, J=8.0 Hz, 2H), 6.56 (d, J=2.4 Hz, 2H), 6.50-6.39 (m, 2H), 5.60 (m,2H), 5.02-4.89 (m, 1H), 4.72 (m, 2H), 3.72 (m, 12H), 1.56 (m, 2H), 1.26(m, 5H), 0.83 (t, J=7.2 Hz, 3H) ppm. MS: M/e 550 (M+1)+.

Step C: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperazin-1-carboxylate

To a solution of4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-formaldehyde(200 mg, 0.384 mmol) and tert-butyl piperazin-1-carboxylate (143 mg,0.768 mmol) in THF (5 mL), AcOH (46 mg, 0.768 mmol) and NaBH(AcO)₃ (244mg, 1.152 mmol) were added. The reaction mixture was stirred at 25° C.for 4 h. After completion of the reaction, the reaction mixture wasquenched with water (20 mL) and extracted with EtOAc (3×30 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (40%) inpetroleum ether to obtain the title compound (230 mg, 83%) as a whitesolid. MS: M/e 719.9 (M+1)+.

Step D:2-(pent-2-yloxy)-7-(piperazin-1-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

2-(pent-2-yloxy)-7-(piperazin-1-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amineTert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperazin-1-carboxylate(230 mg, 0.319 mmol) was dissolved in TFA (8 mL) and H₂O (0.8 mL) underN₂. The reaction mixture was stirred at 70° C. for 3 h. After completionof the reaction, the reaction mixture was quenched with an aqueousNaHCO₃ solution (30 mL) and extracted with EtOAc (3×30 mL). The combinedorganic layers were dried over Na₂SO₄ and concentrated under vacuum toobtain a residue. The residue was purified by preparative TLC(DCM/MeOH=5/2) to obtain the title compound (23 mg, 23%). ¹H NMR (300MHz, DMSO-d₆) δ 8.12 (m, 2H), 7.44 (s, 1H), 4.98 (dd, J=12.4, 6.4 Hz,1H), 3.82 (s, 2H), 3.04-2.92 (m, 4H), 2.58 (s, 4H), 1.72-1.47 (m, 2H),1.37 (m, 2H), 1.28 (d, J=6.4 Hz, 3H), 0.90 (t, J=7.2 Hz, 3H) ppm. MS:M/e 320.40 (M+1)+.

Compound B10:2-(((S)-pent-2-yl)oxy)-7-(piperidin-3-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl3-((4-(bis(3,4-dimethylbenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a cooled solution of(S)—N,N-bis(3,4-dimethylbenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4(200 mg, 0.38 mmol) in THF (8 mL) at −78° C. under the protection of N₂,n-BuLi (1.6 M, 0.4 mL) was added dropwise. After the mixture was stirredat −78° C. for 30 min, a solution of tert-butyl3-formylpiperidin-1-carboxylate (98 mg, 0.46 mmol) in THF (2 mL) wasadded. The resulting mixture was stirred at this temperature for 30 min,and then gradually warmed to room temperature to react overnight. Thesolution was quenched with an NH₄Cl solution (5 mL) and extracted withethyl acetate (10 mL). The organic layer was dried over Na₂SO₄, filteredand concentrated to obtain a crude product, which was further purifiedby CombiFlash (PE:EA=40%) to obtain the pure product (110 mg, 39%). MS:M/e 671 (M+1)+

Step B:2-(((S)-pent-2-yl)oxy)-7-(piperidin-3-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

A solution of the product of step A (110 mg, 0.15 mmol) intrifluoroacetic acid and water (9:1, v/v, 2 mL) was heated at 40° C.overnight. The solvent was evaporated using an oil pump to obtain aresidue, water (5 mL) was added to the residue, and the mixture waspulped and filtered. The filtrate was extracted with DCM (5 mL). Theaqueous phase was alkalized with a 1 M NaOH solution to pH=13, and thenextracted with DCM/MeOH (10 mL, 20%). The organic layer was drying andconcentrated to obtain an intermediate. The intermediate was dissolvedin triethylsilane/trifluoroacetic acid (1:1, v/v, 2 mL) and heated at80° C. overnight. After evaporation, water was added to the residue, themixture was alkalized to pH=13 with 1 M NaOH solution, and extractedwith DCM/MeOH (10 mL, 20%). The organic layer was dried, concentratedand purified by preparative TLC (DCM:NH₃.MeOH=9:1, 4 M NH₃.MeOH) toobtain the product (6 mg, 13%). ¹H NMR (400 MHz, DMSO-d6) δ 8.12 (s,1H), 8.01 (s, 1H), 7.32 (s, 1H), 7.14 (s, 1H), 5.01-4.97 (m, 1H), 3.61(t, J=4.0 Hz, 2H), 3.10 (t, J=12.0 Hz, 2H), 2.76 (d, 0.1=8.0 Hz, 2H),2.68 (t, J=8.0 Hz, 1H), 1.97 (br.s, 1H), 1.78-1.65 (m, 4H), 1.58-1.49(m, 2H), 1.43-1.33 (m, 2H), 1.28 (d, J=4.0 Hz, 3H), 1.23-1.17 (m, 2H),0.91 (t, J=8.0 Hz, 3H) ppm. MS. M/e 319 (M+1)⁺

Compound B11:2-pentyl-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:(E)-N,N-bis(4-methoxybenzyl)-2-(pent-1-en-1-yl)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of2-chloro-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(0.5 g, 1.2 mmol), a mixture of (E)-pent-1-en-1-yl boric acid (0.21 g,1.8 mmol), Pd(dppf)₂Cl₂ (45 mg, 0.06 mmol) and Na₂CO₃ (0.26 g, 2.4 mmol)in dioxane (10 ml) and H₂O (3 ml) was stirred at 80° C. under N₂atmosphere overnight. After completion of the reaction, the mixture wasconcentrated, diluted with EA (20 ml), and then washed with brine (10ml). The organic layer was dried and evaporated under reduced pressure.The resulting residue was purified by flash column chromatography elutedwith 0-25% EA in PE to obtain the product (0.5 g, 92%) as colorless oil.MS: M/e 444 (M+1)⁺.

Step B: Tert-butyl(E)-4-((4-(bis(4-methoxybenzyl)amino)-2-(pent-1-en-1-yl)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of(E)-N,N-bis(4-methoxybenzyl)-2-(pent-1-en-1-yl)imidazo[2,1-f][1,2,4]triazin-4-amine(0.5 g, 1.1 mmol) in THF (15 ml) at −70° C. under N₂, n-BuLi (1.6 M, 1.4ml, 2.2 mmol) was added dropwise. The solution was stirred at −70° C.for 0.5 h. A solution of tert-butyl 4-formylpiperidin-1-carboxylate(0.47 g, 2.2 mmol) in THF (2 ml) was added dropwise to the abovesolution at −70° C. over 0.5 h, and then the mixture was warmed to roomtemperature to react for 1 h. After completion of the reaction, thesolution was quenched with H₂O (15 ml) and extracted with EA (15 ml×2).The organic layer was washed with brine (10 ml), dried and concentrated.The resulting residue was purified by combi-flash eluted with 10%-70% EAin PE to obtain a white semi-solid product (0.65 g, 88%). MS: M/e 657(M+1)⁺.

Step C: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-pentylimidazolo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

A mixture of tert-butyl(E)-4-((4-(bis(4-methoxybenzyl)amino)-2-(pent-1-en-1-yl)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate(0.65 g, 0.99 mmol) and Pd/C (0.1 g) in MeOH (15 ml) was stirred at roomtemperature under H₂ atmosphere overnight. After completion of thereaction, the mixture was filtered through diatomite, and thenevaporated under reduced pressure to obtain the product (0.6 g, 92%) aswhite oil. MS: M/e 659 (M+1)⁺.

Step D:2-pentyl-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-pentylimidazolo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate(0.6 g, 0.91 mmol) in TFA (8 ml) and triethylsilane (2 ml) was stirredat 80° C. for 2 d, and then stirred at 100° C. for 2 d. The mixture wasconcentrated under reduced pressure. The residue was diluted with anaqueous NaHCO₃ solution (20 ml) and then extracted with EA (20 ml×3).The organic lay was dried and concentrated. The resulting residue waspurified by preparative TLC and then by preparative HPLC to obtain theproduct (28 mg). ¹H NMR (400 MHz, DMSO-d6) δ 8.59 (s, 1H), 8.35-7.98 (m,3H), 7.50-7.38 (m, 1H), 3.24 (d, J=12.7 Hz, 2H), 2.90-2.75 (m, 4H), 2.57(t, J=7.5 Hz, 2H), 2.06-1.92 (m, 1H), 1.81-1.65 (m, 4H), 1.44-1.25 (m,6H), 0.87 (t, J=6.8 Hz, 3H) ppm. MS. M/e 303 (M+1)⁺.

Compound B12:(S)-7-((1-(2-(methylamino)ethyl)piperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(S)-(2-(4-((4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)ethyl)(methyl)carbamate

At room temperature, to a mixture of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine(20 mg, 0.063 mmol) and tert-butyl (2-oxoethyl)carbamate (20 mg, 0.116mmol) in THF (1 mL), AcOH (20 mg, 0.33 mmol) was added, then NaBH(OAc)₃(40 mg, 0.189 mmol) was added, and the mixture was stirred for 16 h. 2mL of brine was added and the mixture was extracted with EA (2 mL×3).The combined extracts were washed with brine (5 mL×3), dried over Na₂SO₄and concentrated. The resulting residue was purified by preparative TLC(CH2Cl2/MeOH (NH3 solution)=15:1) to obtain the title product (15 mg,50%). MS: M/e 476 (M+1)⁺.

Step B:(S)-7-((1-(2-(methylamino)ethyl)piperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

The product of step A (15 mg, 0.032 mmol) in HCl/EA solution (4 M, 5 mL)was stirred at room temperature for 5 h. The mixture was concentrated,alkalized with NaOH (4 M, aqueous solution) and extracted with CH₂Cl₂ (2mL×3). The combined extracts were washed with brine (5 mL×3), dried overNa₂SO₄ and concentrated. The resulting residue was purified bypreparative TLC (CH₂Cl₂/MeOH (NH₃ solution)=15:1) to obtain the titleproduct (4.5 mg, 38%). ¹H NMR (400 MHz, CD3OD) δ 7.38 (s, 1H), 5.19-5.04(m, 1H), 3.69-3.54 (m, 2H), 3.54-3.35 (m, 4H), 3.09-2.85 (m, 4H), 2.78(s, 3H), 2.20-2.06 (m, 1H), 2.00-1.89 (m, 2H), 1.84-1.66 (m, 3H),1.67-1.41 (m, 3H), 1.36 (d, J=6.4 Hz, 3H), 0.97 (t, J=7.2 Hz, 3H) ppm.MS: M/e 376 (M+1)⁺.

Compound B13:2-(((S)-pent-2-yl)oxy)-7-((1-(pyrrolidin-3-yl)piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl3-(4-((4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)pyrrolidin-1-carboxylate

To a stirred solution of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine(20 mg, 0.063 mmol) and tert-butyl 3-oxopyrrolidin-1-carboxylate (23 mg,0.126 mmol) in THF (5 mL), AcOH (2 droplets) was added. The mixture wasthen stirred at room temperature for half an hour, and then NaBH(OAc)₃(27 mg, 0.126 mmol) was added. Thereafter, the reaction mixture wasstirred for two days. The reaction mixture was concentrated to obtain aresidue, and the residue was purified by preparative TLC(CH₂Cl₂/MeOH=10:1) to obtain the target compound (22 mg, 71.7%). MS: M/e488 (M+1)⁺.

Step B:2-(((S)-pent-2-yl)oxy)-7-((1-(pyrrolidin-3-yl)piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of the product of step A (22 mg, 0.045 mmol) in EtOAc/HCl (4.0M, 5 mL) was stirred overnight. The reaction mixture was concentrated toobtain a residue, and the residue was purified by preparative HPLC toobtain the target compound (5 mg). ¹H NMR (400 MHz, DMSO-d₆) δ 9.83 (s,1H), 9.22 (s, 1H), 9.06 (s, 1H), 8.12 (s, 1H) 8.05 (s, 1H), 7.36 (s,1H), 5.02-4.93 (m, 1H), 3.94-3.89 (m, 1H), 3.65-3.58 (m, 1H), 3.55-3.28(m, 4H), 3.27-2.86 (m, 4H), 2.79 (d, J=6.4 Hz, 2H), 2.38-2.31 (m, 1H),2.16-1.92 (m, 2H), 1.86-1.77 (m, 2H), 1.73-1.49 (m, 2H), 1.48-1.35 (m,4H), 1.28 (d, J=6.0 Hz, 3H), 0.91 (t, J=7.2 Hz, 3H) ppm. MS: M/e 388(M+1)⁺.

Compound B14:(S)-2-(pent-2-yloxy)-7-((1-(piperidin-4-ylmethyl)piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(S)-4-((4-((4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)methyl)piperidin-1-carboxylate

A mixture of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine(20 mg, 0.06 mmol), tert-butyl 4-formylpiperidin-1-carboxylate (27 mg,0.12 mmol) and sodium triacetoxyborohydride (27 mg, 0.12 mmol) in THF (5mL) was stirred at room temperature for 3 h. The mixture was extractedwith DCM (20 mL), washed with water (5 ml), concentrated and purified bycolumn chromatography (DCM/MeOH=20:1-3:1) to obtain the title product(30 mg, 92.62%). MS: M/e 516 (M+1)⁺.

Step B:(S)-2-(pent-2-yloxy)-7-((1-(piperidin-4-ylmethyl)piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of tert-butyl(S)-4-((4-((4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-methyl)piperidin-1-carboxylate(30 mg, 0.06 mmol) and TFA (0.5 mL) in DCM (3 mL) was stirred at roomtemperature for 2 h. The mixture was concentrated and purified bypreparative HPLC to obtain the product (18 mg, 74.46%). ¹H NMR (400 MHz,DMSO-d6) δ 8.93 (s, 1H), 8.55 (s, 1H), 8.31 (s, 1H), 8.14 (s, 1H), 8.06(s, 1H), 7.37 (s, 1H), 5.01-4.97 (m, 1H), 3.48 (d, J=11.8 Hz, 2H),3.38-3.18 (m, 3H), 2.96 (t, J=5.9 Hz, 2H), 2.92-2.81 (m, 4H), 2.79 (d,J=6.3 Hz, 2H), 2.07 (s, 1H), 1.95 (s, 1H), 1.83 (t, J=14.5 Hz, 4H),1.70-1.63 (m, 1H), 1.58-1.42 (m, 3H), 1.42-1.31 (m, 3H), 1.28 (d, J=6.1Hz, 3H), 0.91 (t, J=7.3 Hz, 3H) ppm. MS: M/e 416 (M+1)⁺.

Compound B15:7-(((R)-3-methylpiperazin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(2R)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)-2-methylpiperazin-1-carboxylate

At room temperature, to a mixture of4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-formaldehyde(100 mg, 0.18 mmol) and tert-butyl (R)-2-methylpiperazin-1-carboxylate(72 mg, 0.36 mmol) in THF (2 mL), AcOH (25 mg, 0.42 mmol) and thenNaBH(OAc)₃ (115 mg, 0.54 mmol) were added, and the resulting mixture wasstirred for 16 h. 2 mL of brine was added and the mixture was extractedwith EA (2 mL×3). The combined extracts were washed with brine (2 mL×3),dried over Na₂SO₄ and concentrated. The resulting residue was purifiedby preparative TLC (PE/EA=1:1) to obtain the title product (85 mg, 64%).MS: M/e 734 (M+1)⁺.

Step B:7-(((R)-3-methylpiperazin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

The product of step A (85 mg, 0.12 mmol) in HCl/EA solution (4 M, 5 mL)was stirred at room temperature for 16 h. The mixture was concentratedto dryness, 5 mL of TFA was added, and the resulting mixture was stirredat room temperature for 2 h and then at 60° C. for 5 h. The mixture wasconcentrated to dryness under high vacuum. 2 mL of NaOH (aqueoussolution, 4 M) was added and the mixture was extracted with CH₂Cl₂ (5mL×5). The combined extracts were washed with brine (10 mL×3), driedover Na₂SO₄ and concentrated. The resulting residue was purified bypreparative TLC (CH₂Cl₂/MeOH (NH₃ solution)=10:1) to obtain the titleproduct (25 mg, 65%). ¹H NMR (400 MHz, CD3OD) δ 7.49 (s, 1H), 5.22-5.06(m, 1H), 4.05-3.87 (m, 2H), 3.17-2.91 (m, 5H), 2.38-2.22 (m, 1H),2.08-1.96 (m, 1H), 1.83-1.69 (m, 1H), 1.69-1.56 (m, 1H), 1.55-1.40 (m,2H), 1.40-1.30 (m, 3H), 1.20-1.07 (m, 3H), 1.00-0.91 (m, 3H) ppm. MS:M/e 334 (M+1)⁺.

Compound B16:7-(((S)-3-methylpiperazin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(2S)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)-2-methylpiperazin-1-carboxylate

At room temperature, to a mixture of4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-formaldehyde(100 mg, 0.18 mmol) and tert-butyl (S)-2-methylpiperazin-1-carboxylate(72 mg, 0.36 mmol) in THF (2 mL), AcOH (25 mg, 0.42 mmol) and thenNaBH(OAc)₃ (115 mg, 0.54 mmol) were added, and the resulting mixture wasstirred for 16 h. 2 mL of brine was added and the mixture was extractedwith EA (2 mL×3). The combined extracts were washed with brine (2 mL×3),dried over Na₂SO₄ and concentrated. The resulting residue was purifiedby preparative TLC (PE/EA=1:1) to obtain the title product (92 mg, 68%).MS: M/e 734 (M+1)⁺.

Step B:7-(((S)-3-methylpiperazin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

The product of step A (92 mg, 0.12 mmol) in HC/EA solution (4 M, 5 mL)was stirred at room temperature for 16 h. The mixture was concentratedto dryness, 5 mL of TFA was added, and the resulting mixture was stirredat room temperature for 2 h and then at 60° C. for 5 h. The mixture wasconcentrated to dryness under high vacuum. 2 mL of NaOH (aqueoussolution, 4 M) was added and the mixture was extracted with CH₂Cl₂ (5mL×5). The combined extracts were washed with brine (10 mL×3), driedover Na₂SO₄ and concentrated. The resulting residue was purified bypreparative TLC (CH₂Cl₂/MeOH (NH solution)=10:1) to obtain the titleproduct (21 mg, 50%). ¹H NMR (400 MHz, CD3OD) δ 7.48 (s, 1H), 5.17-5.06(m, 1H), 3.93 (s, 2H), 3.12-2.90 (m, 5H), 2.35-2.22 (m, 1H), 1.99 (t,J=10.8 Hz, 1H), 1.85-1.69 (m, 1H), 1.69-1.55 (m, 1H), 1.53-1.39 (m, 2H),1.36 (d, J=6.0 Hz, 3H), 1.12 (d, J=6.4 Hz, 3H), 0.96 (t, J=7.2 Hz, 3H)ppm. MS: M/e 334 (M+1)⁺.

Compound B17:7-(((S)-2-methylpiperazin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(3S)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)-3-methylpiperazin-1-carboxylate

At room temperature, to a mixture of4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-formaldehyde(100 mg, 0.18 mmol) and tert-butyl (S)-3-methylpiperazin-1-carboxylate(72 mg, 0.36 mmol) in THF (2 mL), AcOH (25 mg, 0.42 mmol) and thenNaBH(OAc)₃ (115 mg, 0.54 mmol) were added, and the resulting mixture wasstirred for 16 h. 2 mL of brine was added and the mixture was extractedwith EA (2 mL×3). The combined extracts were washed with brine (2 mL×3),dried over Na₂SO₄ and concentrated. The resulting residue was purifiedby preparative TLC (PE/EA=1:1) to obtain the title product (86 mg, 64%).MS: M/e 734 (M+1)⁺.

Step B:7-(((S)-2-methylpiperazin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Tert-butyl(3S)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)-3-methylpiperazin-1-carboxylate(86 mg, 0.12 mmol) in HCl/EA (4 M, 5 mL) solution was stirred at roomtemperature for 16 h. The mixture was concentrated to dryness, 5 mL ofTFA was added, the resulting mixture was stirred at room temperature for2 h and then at 60° C. for 5 h. The mixture was concentrated to drynessunder high vacuum. 2 mL of NaOH (aqueous solution, 4 M) was added andthe mixture was extracted with CH₂Cl₂ (5 mL×5). The combined extractswere washed with brine (10 mL×3), dried over Na₂SO₄ and concentrated.The resulting residue was purified by preparative TLC (CH₂Cl₂/MeOH (NH₃solution)=10:1) to obtain the title product (15 mg, 38%). ¹H NMR (400MHz, CD3OD) δ 7.49 (s, 1H), 5.17-5.02 (m, 1H), 4.26 (d, J=14.8 Hz, 1H),3.92 (dd, J=14.8, 5.2 Hz, 1H), 3.11-3.04 (m, 2H), 3.03-2.97 (m, 1H),2.96-2.86 (m, 1H), 2.70-2.51 (m, 2H), 2.46-2.34 (m, 1H), 1.83-1.70 (m,1H), 1.67-1.55 (m, 1H), 1.55-1.39 (m, 2H), 1.36 (dd, J=6.0, 0.8 Hz, 3H),1.31 (d, J=6.0 Hz, 3H), 0.96 (t, J=7.2 Hz, 3H) ppm. MS: M/e 334 (M+1)⁺.

Compound B18:7-(((R)-2-methylpiperazin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl (3R)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl-3-methylpiperazin-1-carboxylate

At room temperature, to a mixture of4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-formaldehyde(100 mg, 0.18 mmol) and tert-butyl (R)-3-methylpiperazin-1-carboxylate(72 mg, 0.36 mmol) in THF (2 mL), AcOH (25 mg, 0.42 mmol) and thenNaBH(OAc)₃ (115 mg, 0.54 mmol) were added, and the resulting mixture wasstirred for 16 h. 2 mL of brine was added and the mixture was extractedwith EA (2 mL×3). The combined extracts were washed with brine (2 mL×3),dried over Na₂SO₄ and concentrated. The resulting residue was purifiedby preparative TLC (PE/EA=1:1) to obtain the title product (82 mg, 62%).MS: M/e 734 (M+1)⁺.

Step B:7-(((R)-2-methylpiperazin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Tert-butyl(3R)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)-3-methylpiperazin-1-carboxylate(82 mg, 0.11 mmol) in HC/EA (4 M, 5 mL) solution was stirred at roomtemperature for 16 h. The mixture was concentrated to dryness, 5 mL ofTFA was added, the resulting mixture was stirred at room temperature for2 h and then at 60° C. for 5 h. The mixture was concentrated to drynessunder high vacuum. 2 mL of NaOH (aqueous solution, 4 M) was added andthe mixture was extracted with CH₂Cl₂ (5 mL×5). The combined extractswere washed with brine (10 mL×3), dried over Na₂SO₄ and concentrated.The resulting residue was purified by preparative TLC (CH₂Cl₂/MeOH (NH,solution)=10:1) to obtain the title product (13 mg, 35%). ¹H NMR (400)MHz, CD3OD) δ 7.49 (s, 1H), 5.21-5.01 (m, 1H), 4.25 (d, J=14.8 Hz, 1H),3.92 (dd, J=14.8, 5.6 Hz, 1H), 3.06-2.93 (m, 3H), 2.92-2.81 (m, 1H),2.64-2.45 (m, 2H), 2.43-2.31 (m, 1H), 1.82-1.70 (m, 1H), 1.67-1.55 (m,1H), 1.54-1.40 (m, 2H), 1.36 (d, J=6.0 Hz, 3H), 1.30 (d, J=5.6 Hz, 3H),0.96 (t, J=7.2 Hz, 3H) ppm. MS: M/e 334 (M+1)⁺.

Compound B19:(S)-7-((1-(3-(methylamino)propyl)piperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl (3-oxopropyl)methyl carbamate

At −78° C. under N₂, to a solution of oxalyl chloride (510 mg, 4.0 mmol)in CH₂Cl₂ (5 mL), a solution of DMSO (624 mg, 8.0 mmol) in CH₂Cl₂ (5 mL)was added. The mixture was stirred for 20 min. A solution of tert-butyl(3-hydroxypropyl)(methyl)carbamate (500 mg, 2.64 mmol) in CH₂Cl₂ (5 mL)was added at a temperature below −55° C. The resulting mixture wasstirred at −78° C. for 30 min and then at −50° C. for 30 min. A solutionof Et₃N (1.54 g, 15.2 mmol) in CH₂Cl₂ (5 mL) was added, and the mixturewas stirred at room temperature for 16 h. The mixture was diluted with20 mL of CH₂Cl₂ and washed with brine (5 mL×3), dried over Na₂SO₄ andconcentrated. The resulting residue was purified by columnchromatography (PE/EA=5:1) to obtain the title product (180 mg, crude).MS: M/e 188 (M+1)⁺.

Step B: Tert-butyl(S)-(3-(4-((4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)propyl)(methyl)carbamate

At room temperature, to a mixture of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine(20 mg, 0.063 mmol) and tert-butyl (3-oxopropyl)carbamate (26 mg, crude)in THF (1 mL), AcOH (20 mg, 0.33 mmol) and then NaBH(OAc)₃ (40 mg, 0.189mmol) were added, and the resulting mixture was stirred for 16 h. 2 mLof brine was added and the mixture was extracted with EA (2 mL×3). Thecombined extracts were washed with brine (2 mL×3), dried over Na₂SO₄ andconcentrated. The resulting residue was purified by preparative TLC(CH2Cl2/MeOH (NH3 solution)=15:1) to obtain the title product (17 mg,55%). MS: M/e 490 (M+1)⁺.

Step C:(S)-7-((1-(3-(methylamino)propyl)piperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

The product of step B (17 mg, 0.035 mmol) in HCl/EA solution (4 M, 5 mL)was stirred at room temperature for 5 h. The mixture was concentrated,alkalized with NaOH (4 M, aqueous solution) and extracted with CH₂Cl₂ (2mL×5). The combined extracts were washed with brine (5 mL×3), dried overNa₂SO₄ and concentrated. The resulting residue was purified bypreparative TLC (CH₂Cl₂/MeOH (NH3 solution)=10:1) to obtain the titleproduct (3.5 mg, 26%). ¹H NMR (400 MHz, CD3OD) δ 7.35 (d, J=5.2 Hz, 1H),5.18-5.05 (m, 1H), 3.46-3.34 (m, 2H), 3.11-3.04 (m, 2H), 3.03-2.85 (m,4H), 2.72 (s, 3H), 2.14-1.99 (m, 3H), 1.97-1.84 (m, 2H), 1.82-1.68 (m,1H), 1.67-1.41 (m, 5H), 1.36 (d, J=6.0 Hz, 1H), 0.97 (t, J=7.2 Hz, 3H)ppm. MS: M/e 390 (M+1)⁺.

Compound B20:2-(((S)-pent-2-yl)oxy)-7-((1-(pyrrolidin-2-ylmethyl)piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl2-((4-(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)methyl)pyrrolidin-1-carboxylate

To a stirred solution of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine(20 mg, 0.063 mmol) and tert-butyl 2-formylpyrrolidin-1-carboxylate (25mg, 0.126 mmol) in THF (5 mL), AcOH (2 droplets) was added. The mixturewas then stirred at room temperature for half an hour, and thenNaBH(OAc)₃ (27 mg, 0.126 mmol) was added. Thereafter, the reactionmixture was stirred overnight. The reaction mixture was concentrated toobtain a residue, and the residue was purified by preparative TLC(CH₂Cl₂/MeOH=10:1) to obtain the target compound (23 mg, 72.8%). MS: M/e502 (M+1)⁺.

Step B:2-(((S)-pent-2-yl)oxy)-7-((1-(pyrrolidin-2-ylmethyl)piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of the product of step A (22 mg, 0.045 mmol) in EtOAc/HCl (4.0M, 5 mL) was stirred overnight. The reaction mixture was concentrated toobtain a residue, and the residue was purified by preparative HPLC toobtain the target compound (10 mg). ¹H NMR (400 MHz, DMSO-d₆) δ 9.33 (s,1H), 9.08 (s, 1H), 8.84 (s, 1H), 8.14 (s, 1H), 8.06 (s, 1H), 7.37 (s,1H), 5.06-4.94 (m, 1H), 3.94 (s, 1H), 3.66-3.30 (m, 4H), 3.24 (s, 2H),3.08-2.71 (m, 4H), 2.22-2.10 (m, 1H), 2.09-1.74 (m, 5H), 1.73-1.60 (m,2H), 1.61-1.34 (m, 5H), 1.28 (d, J=6.0 Hz, 3H), 0.91 (t, J=7.2 Hz, 3H)ppm. MS: M/e 402 (M+1)⁺.

Compound B21:7-((4-(methylamino)piperidin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(1-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-4-yl)(methyl)carbamate

To a solution of4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-formaldehyde(200 mg, 0.364 mmol) and tert-butyl methyl(piperidin-4-yl)carbamate (136mg, 0.732 mmol) in THF (5 mL), AcOH (44 mg, 0.733 mmol) and NaBH(AcO)₃(233 mg, 1.09 mmol) were added. The reaction mixture was stirred at 25°C. for 3 h. After completion of the reaction, the reaction mixture wasquenched with water (20 mL) and extracted with EtOAc (3×30 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (80%) inpetroleum ether to obtain the title compound (230 mg, 85%). MS: M/e 748(M+1)⁺.

Step B:7-((4-(methylamino)piperidin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

The product of step A (230 mg, 0.307 mmol) was dissolved in TFA (5 mL)under N₂. The reaction mixture was stirred at 70° C. for 12 h. Aftercompletion of the reaction, the reaction mixture was quenched with anaqueous NaHCO₃ solution (30 mL) and extracted with EtOAc (3×30 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by preparative HPLCunder the following conditions: column: XBridge Prep C18 OBD column19×150 mm 5 um; mobile phase A: water (0.1% TFA), mobile phase B: ACN;flow rate: 17 mL/min; gradient: 5% B to 30% B in 11 min; 214/254 nm,thereby obtaining the title compound (64 mg, 30%). ¹H NMR (400 MHz,DMSO-d₆) δ 8.93 (br.s, 2H), 8.39 (s, 1H), 8.29 (s, 1H), 7.66 (s, 1H),5.05 (dd, J=12.4, 6.4 Hz, 1H), 4.57 (s, 2H), 3.57 (s, 3H), 3.20-3.03 (m,3H), 2.55 (s, 3H), 2.19 (d, J=12.4 Hz, 2H), 1.88-1.60 (m, 3H), 1.59-1.47(m, 1H), 1.46-1.31 (m, 2H), 1.28 (d, J=6.4 Hz, 3H), 0.91 (t, J=7.2 Hz,3H) ppm. MS: M/e 348 (M+1)⁺.

Compound B22:7-((4-(methylamino)methyl)piperidin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl((1-(4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-][1,2,4]triazin-7-yl)methyl)piperidin-4-yl)methyl)(methyl)carbamate

To a solution of4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-formaldehyde(200 mg, 0.364 mmol) and tert-butyl methyl(piperidin-4-yl)carbamate (166mg, 0.728 mmol) in THF (5 mL), AcOH (44 mg, 0.733 mmol) and NaBH(AcO)₃(233 mg, 1.09 mmol) were added. The reaction mixture was stirred at 25°C. for 3 h. After completion of the reaction, the reaction mixture wasquenched with water (20 mL) and extracted with EtOAc (3×30 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (80%) inpetroleum ether to obtain the title compound (210 mg, 76%). MS: M/e 762(M+1)⁺.

Step B:7-((4-(methylamino)methyl)piperidin-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Tert-butyl((1-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-4-yl)methyl)(methyl)carbamate(210 mg, 0.276 mmol) was dissolved in TFA (5 mL) under N₂. The reactionmixture was stirred at 70° C. for 12 h. After completion of thereaction, the reaction mixture was quenched with an aqueous NaHCO₃solution (30 mL) and extracted with EtOAc (3×30 mL). The combinedorganic layers were dried over Na₂SO₄ and concentrated under vacuum toobtain a residue. The residue was purified by preparative HPLC under thefollowing conditions: column: XBridge Prep C18 OBD column 19×150 mm 5um: mobile phase A: water (0.1% TFA), mobile phase B: ACN; flow rate: 17mL/min: gradient: 5% B to 30% B in 11 min; 214/254 nm, thereby obtainingthe title compound (15 mg, 15%). ¹H NMR (400 MHz, DMSO-d₆) δ 10.05(br.s, 1H), 8.56 (br.s, 2H), 8.40-8.25 (m, 2H), 7.67 (s, 1H), 5.06 (dd,J=12.4, 6.4 Hz, 1H), 4.54 (s, 2H), 3.45-3.35 (m, 2H), 3.02 (s, 3H), 2.82(d, J=4.4 Hz, 2H), 2.55 (t, J=5.2 Hz, 3H), 1.90 (d, J=13.2 Hz, 3H),1.73-1.49 (m, 2H), 1.49-1.31 (m, 4H), 1.28 (d, J=6.4 Hz, 3H), 0.91 (t,J=7.2 Hz, 3H) ppm. MS: M/e 362 (M+1)⁺.

Compound B23:(S)-7-([1,4′-bipiperidin]-4-ylmethyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A. Tert-butyl(S)-4-((4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)tert-butyl-[1,4′-bipiperidin]-1′-carboxylate

A mixture of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine(20 mg, 0.06 mmol), tert-butyl 4-oxopiperidin-1-carboxylate (19 mg, 0.09mmol) and titanium tetraisopropoxide (54 mg, 0.19 mmol) in EtOH (5 mL)was stirred at room temperature for 3 h. Then, sodium borohydride (27mg, 0.12 mmol) was added and the mixture was stirred at room temperaturefor 1 h. The mixture was quenched with water (0.5 mL), extracted withDCM (20 mL), washed with water (5 ml), concentrated and purified bycolumn chromatography (DCM/MeOH=20:1-3:1) to obtain the product (29 mg,92.04%). MS: M/e 502 (M+1)⁺.

Step B:(S)-7-([1,4′-bipiperidin]-4-ylmethyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of the product of step A (29 mg, 0.06 mmol) and TFA (0.5 mL)in DCM (3 mL) was stirred at room temperature for 2 h. The mixture wasconcentrated and purified by preparative HPLC to obtain the product (18mg, 74.5%). ¹H NMR (400 MHz, DMSO-d6) δ 9.40 (br.s, 1H), 8.73 (d, J=9.1Hz, 1H), 8.43 (d, J=10.1 Hz, 1H), 8.11 (s, 1H), 8.03 (s, 1H), 7.35 (s,1H), 5.01-4.99 (m, 1H), 3.48-3.35 (m, 5H), 2.98-2.86 (m, 4H), 2.79 (d,J=6.5 Hz, 2H), 2.15 (d, J=12.1 Hz, 2H), 1.98 (s, 1H), 1.86 (d, J=13.5Hz, 2H), 1.79-1.69 (m, 2H), 1.69-1.62 (m, 1H), 1.60-1.42 (m, 3H),1.42-1.32 (m, 2H), 1.28 (d, J=6.1 Hz, 3H), 0.91 (t, J=7.3 Hz, 3H) ppm.MS: M/e 402 (M+1)⁺.

Compound B24:2-(4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)-7-azaspiro[3.5]nona-2-ol

Step A: Tert-butyl2-(4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)-2-hydroxy-7-azaspiro[3.5]nonan-7-carboxylate

At −78° C. under N₂, to a solution ofN,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(300 mg, 0.576 mmol) in THF (8 mL), n-BuLi (1.8 mL, 2.88 mmol) wasadded. After the mixture was stirred at −78° C. for 0.5 h, tert-butyl2-oxo-7-azaspiro[3.5]nonan-7-carboxylate (165 mg, 0.691 mmol) was added.The reaction mixture was warmed to −78° C. and stirred for 2.5 h. Aftercompletion of the reaction, the reaction mixture was quenched with anaqueous NH₄Cl solution (20 mL) and extracted with EtOAc (3×30 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (40%) inpetroleum ether to obtain the title compound (210 mg, 48%). MS: M/e 761(M+1)⁺.

Step B:2-(4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)-7-azaspiro[3.5]nona-2-ol

Tert-butyl2-(4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)-2-hydroxy-7-azaspiro[3.5]nonan-7-carboxylate(210 mg, 0.276 mmol) was dissolved in TFA (5 mL) and H₂O (0.5 mL) underN₂. The reaction mixture was stirred at 35° C. for 12 h. Aftercompletion of the reaction, the reaction mixture was quenched with anaqueous NaHCO₃ solution (30 mL) and extracted with EtOAc (3×80 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by preparative HPLCunder the following conditions: column: XBridge Prep C18 OBD column 19′150 mm 5 um: mobile phase A: water (0.1% TFA), mobile phase B: ACN; flowrate: 17 mL/min; gradient: 5% B to 45% B in 11 min; 214/254 nm, therebyobtaining the title compound (51 mg, 51%). ¹H NMR (400 MHz, DMSO-d₆) δ8.27 (br.s, 2H), 8.20-7.98 (m, 2H), 7.43 (s, 1H), 5.45 (s, 1H), 4.96(dd, J=12.4, 6.4 Hz, 1H), 3.15-2.80 (m, 5H), 2.74-2.64 (m, 2H), 2.18 (d,J=12.6 Hz, 2H), 1.90 (s, 2H), 1.72-1.46 (m, 4H), 1.45-1.32 (m, 2H), 1.28(t, J=6.4 Hz, 3H), 0.90 (t, J=7.2 Hz, 3H) ppm. MS: M/e 361 (M+1)⁺.

Compound B25:7-(azepan-4-ylmethyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)azepan-1-carboxylate

To a stirred solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(200 mg, 0.383 mmol) in THF (8 mL) cooled to −78° C. under nitrogenatmosphere, n-BuLi (1.6 M in hexane, 0.78 mmol, 0.48 mL) was addeddropwise. After the mixture was stirred for 30 min, a solution oftert-butyl 4-formylazepan-1-carboxylate (150 mg, 0.66 mmol) in THF (2mL) was slowly added. The reaction mixture was slowly warmed to roomtemperature and stirred overnight. The reaction mixture was poured intoa saturated ammonium chloride solution and extracted with EtOAc (15mL×3). The combined organic phases were washed with brine, dried overNa₂SO₄ and concentrated under vacuum. The crude product was purified bycolumn chromatography to obtain the title product (120 mg, 41.3%). MS:M/e 748.9 (M+1)⁺.

Step B:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(azepan-4-yl)methanol

H₂O (2 ml) was added to a stirred mixture of the product of step A (120mg, 0.16 mmol) in TFA (8 ml). Thereafter, the reaction mixture wasstirred at 30° C. overnight. The reaction mixture was cooled to roomtemperature and concentrated under vacuum. 1 M HCl solution (20 ml) wasadded to the residue and the mixture was filtered. The filtrate wasextracted with DCM (20 ml). The aqueous phase was adjusted to a pH of12-13 with 2 M aqueous NaOH solution and extracted with DCM (20 mL×3).The organic phase was washed with brine, dried over Na₂SO₄ andconcentrated under vacuum to obtain the product (35 mg, 62.5%), whichwas directly used in the next step. MS: Me 349 (M+1)⁺.

Step C:7-(azepan-4-ylmethyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (5 ml) was added to a stirred mixture of(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(azepan-4-yl)methanol(35 mg, 0.1 mmol) in TFA (5 ml). Thereafter, the reaction mixture wasstirred at 80° C. for 2 d. The mixture was cooled to room temperatureand concentrated under vacuum. The residue was purified by preparativeHPLC to obtain the target compound (10 mg, 22.4%). ¹H NMR (400 MHz,MeOH-d6) δ 7.59 (s, 1H), 5.18-5.13 (m, 1H), 3.44-3.36 (m, 2H), 3.28 (s,1H), 3.14 (m, 2H), 2.96 (dd, J=16.6, 7.0 Hz, 2H), 2.10-1.95 (m, 2H),1.83-1.75 (m, 2H), 1.72-1.61 (m, 2H), 1.53-1.44 (m, 4H), 1.39 (d, J=6.1Hz, 3H), 1.09-1.04 (m, 1H), 0.99 (t, J=7.3 Hz, 3H) ppm. MS: M/e 333(M+1)⁺.

Compound B26:2-(((S)-pent-2-yl)oxy)-7-(pyrrolidin-3-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl3-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy))methyl)pyrrolidin-1-carboxylate

To a stirred solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(200 mg, 0.383 mmol) in THF (8 mL) cooled to −78° C. under nitrogenatmosphere, n-BuLi (1.6 M in hexane, 0.78 mmol, 0.48 mL) was addeddropwise. After the mixture was stirred for 30 min, a solution oftert-butyl 3-formylpyrrolidin-1-carboxylate (150 mg, 0.75 mmol) in THF(2 mL) was slowly added. The reaction mixture was slowly warmed to roomtemperature and stirred overnight. The reaction mixture was poured intoa saturated ammonium chloride solution and extracted with EtOAc (15mL×3). The combined organic phases were washed with brine, dried overNa₂SO₄ and concentrated under vacuum. The crude product was purified bycolumn chromatography to obtain the title product (110 mg, 40%). MS: M/e721 (M+1)⁺.

Step B:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(pyrrolidin-3-yl)methanol

H₂O (2 ml) was added to a stirred mixture of the product of step A (110mg, 0.152 mmol) in TFA (8 ml). Thereafter, the reaction mixture wasstirred at 30° C. overnight. The reaction mixture was cooled to roomtemperature and concentrated under vacuum. 1 M HCl solution (20 ml) wasadded to the residue and the mixture was filtered. The filtrate wasextracted with DCM (20 ml). The aqueous phase was adjusted to a pH of12-13 with 2 M aqueous NaOH solution and extracted with DCM (20 mL×3).The organic phase was washed with brine, dried over Na₂SO₄ andconcentrated under vacuum to obtain the product (30 mg, 61.4%), whichwas directly used in the next step. MS: M/e 321 (M+1)⁺.

Step C:2-(((S)-pent-2-yl)oxy)-7-(pyrrolidin-3-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (5 ml) was added to a stirred mixture of the product of step B(30 mg, 0.093 mmol) in TFA (5 ml). Thereafter, the reaction mixture wasstirred at 80° C. for 3 d. The mixture was cooled to room temperatureand concentrated under vacuum. The residue was purified by preparativeHPLC to obtain the target compound (12 mg, 32%). ¹H NMR (400 MHz,MeOH-d6) δ 7.90 (s, 1H), 5.44-5.40 (m, 1H), 3.78-3.66 (m, 2H), 3.56-5.53(m, 2H), 3.37 (d, J=7.1 Hz, 2H), 3.34-3.25 (m, 1H), 3.16-3.13 (m, 1H),2.50-2.47 (m, 1H), 2.11-2.03 (m, 2H), 1.89-1.85 (m, 1H), 1.82-1.68 (m,2H), 1.64 (d, J=6.0 Hz, 3H), 1.23 (t, J=7.2 Hz, 3H) ppm. MS: M/e 305(M+1)⁺.

Compound B27:7-((2-methylpiperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl 4-(hydroxymethyl)-2-methylpiperidin-1-carboxylate

BH₃-THF (1 M, 3 mL, 3 mmol) was added to a solution of1-(tert-butoxycarbonyl)-2-methylpiperidin-4-carboxylic acid (243 mg, 1mmol) in THF (10 mL) at 0° C. The reaction mixture was stirred at roomtemperature overnight. An aqueous ammonium chloride solution was addedand the mixture was extracted with ethyl acetate. The combined organicextracts were dried over sodium sulfate, filtered and evaporated toobtain the product (220 mg, 100%), which was directly used in the nextstep. MS: m/e 230 (M+1)⁺.

Step B. Tert-butyl 4-formyl-2-methylpiperidin-1-carboxylate

To a solution of tert-butyl4-(hydroxymethyl)-2-methylpiperidin-1-carboxylate (220 mg, 1 mmol) inDCM (10 mL) at 0° C., Dess-Martin periodinane (636 mg, 1.5 mmol) wasadded. The reaction mixture was stirred at room temperature for 2 h. Anaqueous NaHCO₃ solution was added and the mixture was extracted withethyl acetate. The combined organic extracts were dried over sodiumsulfate, filtered and evaporated. The crude product was purified bycolumn chromatography to obtain the title product (140 mg, 61.7%). ¹HNMR (400 MHz, CDCl₃) δ 9.83 (s, 1H), 4.28 (td, J=6.6, 4.5 Hz, 1H), 3.85(ddd, J=13.9, 5.5, 2.5 Hz, 1H), 2.91 (ddd, J=13.9, 12.7, 3.8 Hz, 1H),2.50 (t, J=4.7 Hz, 1H), 2.15-2.09 (m, 1H), 2.08-2.03 (m, 1H), 1.91 (ddd,J=14.1, 6.4, 2.5 Hz, 1H), 1.71 (dt, J=13.3, 6.4 Hz, 1H), 1.50-1.40 (m,9H), 1.06 (d, J=6.9 Hz, 3H). MS: m/e228 (M+1)⁺.

Step C: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-2-methylpiperidin-1-carboxylate

To a solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(200 mg, 0.38 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 0.48 mL,0.76 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl4-formyl-2-methylpiperidin-1-carboxylate (140 mg, 0.63 mmol) in THF (2mL) was added dropwise. The resulting mixture was stirred at −70° C. for2 h, and then warmed to room temperature to react overnight. Thereaction was quenched with a saturated NH₄Cl solution, extracted withEtOAc (20 mL×3), washed with brine, dried over Na₂SO₄, filtered andconcentrated. The residue was purified by preparative TLC to obtain thetarget compound (110 mg, crude yellow oil). MS: M/e 749 (M+1)⁺.

Step D:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(2-methylpiperidin-4-yl)methanol

H₂O (4 mL) was added to a mixture of the product of step C (110 mg,crude) in TFA (8 mL), and the resulting mixture was stirred at roomtemperature for 2 d. The mixture was concentrated to dryness. H₂O wasadded to the residue and the mixture was filtered. The filtrate waswashed with DCM, and adjusted to a pH of 12-13 with 2 M NaOH solution.The solution was extracted with DCM (20 mL×3). The organic phase waswashed with brine, dried over Na₂SO₄, filtered and concentrated toobtain the target compound (35 mg), which was directly used in the nextstep. MS: M/e 349 (M+1)⁺.

Step E:7-((2-methylpiperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step D (35 mg,crude) in TFA (4 mL), and the resulting mixture was stirred at 85° C.for 2 h. The mixture was cooled to room temperature and concentrated todryness. The residue was purified by preparative HPLC to obtain thetarget compound (17 mg, 34.8% for three steps). ¹H NMR (400 MHz,DMSO-d6) δ 8.73 (s, 1H), 8.13 (br.s, 3H), 7.46 (s, 1H), 5.00 (m, 1H),3.27 (s, 2H), 3.09 (s, 1H), 2.87 (s, 2H), 2.77 (s, 1H), 2.00 (s, 1H),1.78 (s, 2H), 1.66 (s, 1H), 1.57 (s, 1H), 1.38 (s, 3H), 1.28 (d, J=6.0Hz, 3H), 1.16 (d, J=6.2 Hz, 3H), 1.11 (d, J=10.9 Hz, 1H), 0.91 (t, J=7.3Hz, 3H) ppm. MS: M/e 333 (M+1)⁺.

Compound B28:3-((4-amino-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-2-yl)oxy)hexan-1-ol

Step A: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-((1-(tert-butyldimethylsilyl)oxy)hex-3-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of7-bromo-2-((1-((tert-butyldimethylsilyl)oxy)hex-3-yl)oxy)-N,N-bis(2,4-dimethoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(500 mg, 0.671 mmol) in THF (10 mL), n-BuLi (0.9 mL, 1.44 mmol) wasadded at −78° C. under N₂. After the mixture was stirred at −78° C. for0.5 h, tert-butyl 4-formylpiperidin-1-carboxylate (215 mg, 1.01 mmol)was added. The reaction mixture was stirred at −78° C. for 3.5 h. Aftercompletion of the reaction, the reaction mixture was quenched with anaqueous NH₄Cl solution (20 mL) and extracted with DCM (3×30 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (50%) inpetroleum ether to obtain the title compound (310 mg, 53%). MS: M/e 879(M+1)⁺.

Step B:34(4-amino-7-(hydroxy(piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-2-yl)oxy)hexan-1-ol

Tert-butyl 4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-((1-(tert-butyldimethylsilyl)oxy)hex-3-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate(290 mg, 0.329 mmol) was dissolved in TFA (8 mL) and H₂O (0.8 mL) underN₂. The reaction mixture was stirred at 40° C. for 12 h. Aftercompletion of the reaction, the solvent was removed under vacuum. Theresidue was diluted with water (10 mL) and DCM (20 mL), and the aqueousphase was acidified with 1 N HCl to adjust PH=2-3. The aqueous phase waswashed with DCM (3×50 mL), alkalized with 2 N NaOH to adjust PH=13-14,and extracted with DCM/i-PrOH (5/1, 3×60 mL). The combined organiclayers were dried over Na₂SO₄ and concentrated under vacuum to obtainthe title compound (110 mg, 92%). MS: M/e 365 (M+1)⁺.

Step C:3-((4-amino-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-2-yl)oxy)hexan-1-ol

3-((4-amino-7-(hydroxy(piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-2-yl)oxy)hexan-1-ol(110 mg, 0.301 mmol) was dissolved in TFA (4 mL) and Et₃SiH (4 mL) underN₂. The reaction mixture was stirred at 90° C. for 12 h. Aftercompletion of the reaction, the solvent was removed under vacuum. Theresidue was diluted with water (10 mL) and DCM (20 mL), and the aqueousphase was acidified with 1 N HCl to adjust pH=2-3. The aqueous phase waswashed with DCM (3×50 mL), alkalized with 2 N LiOH to adjust PH=13-14,and extracted with DCM/i-PrOH (5/1, 3×60 mL). The combined organiclayers were dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by preparative HPLC under thefollowing conditions; column: XBridge Prep C18 OBD column 19×150 mm 5um: mobile phase A: water (0.1% TFA), mobile phase B: ACN; flow rate: 17mL/min; gradient: 10% B to 30% B in 12 min: 214/254 nm, therebyobtaining the title compound (20 mg, 19%). ¹H NMR (400 MHz, CD₃OD) δ7.42 (s, 1H), 5.30-5.10 (m, 1H), 3.75-3.59 (m, 2H), 3.39 (d, J=12.4 Hz,2H), 3.05-2.85 (m, 4H), 2.64 (s, 1H), 2.16 (s, 1H), 2.05-1.85 (m, 4H),1.83-1.65 (m, 2H), 1.63-1.40 (m, 4H), 0.97 (t, J=7.2 Hz, 3H) ppm. MS:M/e 349 (M+1)⁺.

Compound B29:7-(cyclohexylmethyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:(4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(cyclohexyl)methanol

At −78° C. under N₂, to a solution ofN,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(500 mg, 0.959 mmol) in THF (10 mL), n-BuLi (1.8 mL, 2.88 mmol) wasadded. After the mixture was stirred at −78° C. for 0.5 h, cyclohexylformaldehyde (161 mg, 1.438 mmol) was added. The reaction mixture wasstirred at −78° C. for 2.5 h. After completion of the reaction, thereaction mixture was quenched with an aqueous NH₄Cl solution (30 mL) andextracted with DCM (3×30 mL). The combined organic layers were driedover Na₂SO₄ and concentrated under vacuum to obtain a residue. Theresidue was purified by column chromatography on silica gel eluted withethyl acetate (40%) in petroleum ether to obtain the title compound (560mg, 92%). MS: M/e 634 (M+1)⁺.

Step B:(4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(cyclohexyl)methanol

(4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(cyclohexyl)methanol(560 mg, 0.883 mmol) was dissolved in TFA (8 mL) and H₂O (0.8 mL) underN₂. The reaction mixture was stirred at 35° C. for 12 h. Aftercompletion of the reaction, the solvent was removed under vacuum. Theresidue was diluted with water (20 mL) and DCM (20 mL), and the aqueousphase was extracted with DCM (3×20 mL). The combined organic layers weredried over Na₂SO₄ and concentrated under vacuum to obtain a residue. Theresidue was purified by column chromatography on silica gel eluted withmethanol (NH₃) in dichloromethane (20%) to obtain the title compound(190 mg, 65%). MS. M/e 334 (M+1)⁺.

Step C:7-(cyclohexylmethyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

(4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(cyclohexyl)methanol(190 mg, 0.569 mmol) was dissolved in TFA (5 mL) and Et₃SiH (5 mL) underN₂. The reaction mixture was stirred at 90° C. for 12 h. Aftercompletion of the reaction, the solvent was removed under vacuum. Theresidue was diluted with an aqueous NaHCO₃ solution (20 mL) and DCM (20mL), and the aqueous phase was extracted with DCM (3×20 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (66%) inpetroleum ether to obtain the title compound (20 mg, 11%). ¹H NMR (400MHz, CD₃OD) δ 7.41 (s, 1H), 5.15-5.05 (m, 1H), 2.77 (d, J=6.8 Hz, 2H),1.88-1.56 (m, 9H), 1.55-1.40 (m, 2H), 1.37 (d, J=6.4 Hz, 3H), 1.35-1.19(m, 4H), 1.05 (t, J=10.8 Hz, 2H), 0.98 (t, J=7.2 Hz, 3H) ppm. MS: M/e318 (M+1)⁺.

Compound B30:7-(((1s,3S)-3-aminocyclobutyl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl((1R,3s)-3-((S)-(4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)cyclobutyl)carbamate

At −78° C. under N₂ atmosphere, to a solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(300 mg, 0.57 mmol) in THF (3 mL), n-BuLi (1.6 M, 0.55 mL, 0.88 mmol)was added. The mixture was stirred at −78° C. for 30 min. Then, asolution of tert-butyl ((1s,3s)-3-formylcyclobutyl)carbamate (204 mg,1.02 mmol) in THF (2 mL) was added to the system at −78° C. The reactionwas warmed to room temperature and stirred for 30 min. The reaction wasquenched with a saturated aqueous NH₄Cl solution at room temperature andextracted with EA (10 mL×2). The combined organic phases were washedwith brine (10 mL×2), dried over Na₂SO₄ and concentrated under reducedpressure. The residue was purified by column chromatography to obtainthe title compound (240 mg, yield: 58%). MS: M/e 721 (M+1)⁺.

Step B:(S)-(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)((1s,3R)-3-aminocyclobutyl)methanol

Tert-butyl((1R,3s)-3-((S)-(4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)cyclobutyl)carbamate(240 mg, 0.33 mmol) in TFA/H₂O (9:1, 5 mL) was stirred at roomtemperature for 20 h. The reaction mixture was concentrated underreduced pressure. 10 mL of H₂O was added. The mixture was stirred atroom temperature for 10 min and then filtered. The filtrate wasextracted with DCM (5 mL×2) to remove impurities. The aqueous layer wasalkalized with an aqueous NaOH (4 M) solution to pH>10, and extractedwith DCM/IPA (5:1, 5 mL×3). The combined extracts were washed with brine(5 mL×3), dried over Na₂SO₄ and concentrated to obtain the title product(55 mg, yield: 51%). MS: M/e 321 (M+1)⁺.

Step C:7-(((1s,3S)-3-aminocyclobutyl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of(S)-(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)((1S,3R)-3-aminocyclobutyl)methanol(55 mg, 0.17 mmol), TFA (5 mL) and Et₃SiH (5 mL) was stirred at 60° C.for 16 h. The reaction mixture was concentrated under reduced pressure.The residue was dissolved in H₂O (2.5 mL) and extracted with DCM (2mL×3). The organic phase was discarded. The inorganic phase wasalkalinized with an aqueous NaOH (4 M) solution to pH>10. The mixturewas extracted with DCM/iPrOH (5:1, 2 mL×5). The combined organic phaseswere washed with brine (5 mL×2), dried over Na₂SO₄ and concentrated. Theresidue was purified by preparative TLC (DCM/MeOH(NH₃)=10:1) to obtainthe title compound (8 mg, yield: 15%). ¹H NMR (400 MHz, CD₃OD) δ 7.28(s, 1H), 5.20-5.01 (m, 1H), 3.51-3.35 (m, 1H), 2.96 (d, J=6.0 Hz, 2H),2.58-2.32 (m, 3H), 1.83-1.55 (m, 4H), 1.54-1.39 (m, 2H), 1.36 (d, J=6.0Hz, 3H), 0.96 (t, J=7.2 Hz, 3H) ppm. MS: M/e 305 (M+1)⁺.

Compound B31:(S)-7-((4-(methylamino)cyclohexyl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: (4-(methylamino)cyclohexyl)methanol

At 0° C., To a mixture of4-((tert-butoxycarbonyl)amino)cyclohexan-1-carboxylic acid (5 g, 20.57mmol) in THF (10 mL), LAH (2.35 g, 61.73 mmol) was added in batches andthe resulting mixture was stirred at room temperature for 1 h. Then, themixture was warmed to 60° C. and stirred overnight. The mixture wasquenched with a solution of NaOH (10 mL) and extracted with DCM (50mL×3). The combined organic layers were washed with brine, dried overNa₂SO₄ and concentrated to obtain the target compound (2.20 g, 74.77%)as colorless oil. MS: M/e 144 (M+1)⁺.

Step B: Tert-butyl (4-(hydroxymethyl)cyclohexyl)(methyl)carbamate

A mixture of (4-(methylamino)cyclohexyl)methanol (2 g, 13.99 mmol),di-tert-butyl dicarbonate (3.66 g, 16.78 mmol) and DIPEA (3.61 g, 27.97mmol) in DCM (30 mL) was stirred at room temperature for 2 h. Themixture was quenched with water (10 mL) and extracted with DCM (30mL×3). The combined organic layers were washed with water and brine,dried over Na₂SO₄, and concentrated to obtain tert-butyl(4-(hydroxymethyl)cyclohexyl)(methyl)carbamate (3.26 g, 95.92%) ascolorless oil. MS: M/e 244 (M+1)⁺.

Step C: Tert-butyl (4-formylcyclohexyl)(methyl)carbamate

A mixture of tert-butyl (4-(hydroxymethyl)cyclohexyl)(methyl)carbamate(3 g, 12.35 mmol) and DMP (6.28 g, 14.82 mmol) in DCM (30 mL) wasstirred at room temperature for 2 h. The mixture was filtered, dilutedwith PE, filtered and concentrated to obtain the target compound (2.32g, 77.98%) as yellow oil. MS: M/e 242 (M+1)⁺.

Step D: Tert-butyl(4-((4-(bis(3,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)cyclobutyl)(methyl)carbamate

At −78° C., to a solution of(S)—N,N-bis(3,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(200 mg, 0.3839 mmol) in THF (5 mL), n-butyl lithium (0.29 ml, 0.4607mmol) was added, and the mixture was stirred for 1 h. Then, a solutionof tert-butyl (4-formylcyclohexyl)(methyl)carbamate (139 mg, 0.5758mmol) in THF (1 mL) was added dropwise at −78° C. Thereafter, themixture was warmed to room temperature and stirred for 3 h. The mixturewas quenched with a saturated ammonium chloride solution (5 mL) andextracted with DCM (20 mL×3). The combined organic layers were washedwith brine, dried over Na₂SO₄, concentrated and purified by columnchromatography (DCM/MeOH=20:1-5:1) to obtain the target compound (198mg, 67.60%) as yellow oil. MS: M/e 763 (M+1)⁺.

Step E:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(4-(methylamino)cyclohexyl)methanol

A solution of tert-butyl(4-((4-(bis(3,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)cyclohexyl)(methyl)carbamate(198 mg, 0.2595 mmol) in TFA (2 mL) was stirred at room temperatureovernight. The mixture was concentrated and purified by preparative TLCto obtain(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(4-(methylamino)cyclohexyl)methanol(70 mg, 74.52%) as a white solid. MS: We 363 (M+1).

Step F:(S)-7-((4-(methylamino)cyclohexyl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(4-(methylamino)cyclohexyl)methanol(70 mg, 0.1934 mmol) and triethylsilane (1 mL) in TFA (2 mL) was stirredat 90° C. overnight. The mixture was concentrated and purified bypreparative HPLC to obtain the target compound (35 mg, 52.31%). ¹H NMR(400 MHz, DMSO-d6) δ 8.35 (br. s, 2H), 8.08 (s, 1H), 8.01 (s, 1H), 7.32(s, 1H), 4.97 (dd, J=12.5, 6.5 Hz, 1H), 2.89 (s, 1H), 2.70 (d, J=6.2 Hz,2H), 2.53 (d, J=5.5 Hz, 2H), 2.00 (d, J=10.4 Hz, 2H), 1.71 (m, 4H),1.58-1.50 (m, 1H), 1.42-1.32 (m, 2H), 1.28 (d, J=6.1 Hz, 3H), 1.26-1.13(m, 3H), 1.13-0.98 (m, 2H), 0.91 (t, J=7.2 Hz, 3H) ppm. MS: M/e 347(M+1)⁺.

Compound B32:(S)-7-((1-methylpiperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

At room temperature, to a mixture of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine(65 mg, 0.2 mmol), formaldehyde (30%, 0.5 mL) in MeOH (2 mL), NaBH₃CN(40 mg, 0.63 mmol) was added, and the mixture was stirred for 16 h. Themixture was concentrated and diluted with EA (10 mL), washed with brine(10 mL×3), dried over Na₂SO₄ and concentrated under reduced pressure.The residue was purified by preparative TLC to obtain the title compound(18 mg, yield: 27%). ¹H NMR (400 MHz, CD₃OD) δ 7.32 (s, 1H), 5.18-5.01(m, 1H), 3.02 (d, J=12.0 Hz, 2H), 2.85 (d, J=6.8 Hz, 2H), 2.40 (s, 3H),2.24 (t, J=12.0 Hz, 2H), 1.98-1.82 (m, 1H), 1.82-1.70 (m, 3H), 1.65-1.55(m, 1H), 1.54-1.38 (m, 4H), 1.36 (d, J=6.0 Hz, 3H), 0.97 (t, J=7.2 Hz,3H) ppm. MS: M/e 333 (M+1)⁺.

Compound B33:7-(((1R,5S,6s)-3-azabicyclo[3.1.0]hex-6-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(1R,5S,6r)-6-((S)-(4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-3-azabicyclo[3.1.0]hexan-3-carboxylate

At −78° C. under N₂ atmosphere, to a solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(300 mg, 0.57 mmol) in THF (3 mL, n-BuLi (1.6 M, 0.55 mL, 0.88 mmol) wasadded. The mixture was stirred at −78° C. for 30 min. Then, a solutionof tert-butyl (1R,5S,6r)-6-formyl-3-azabicyclo[3.1.0]hexan-3-carboxylate(218 mg, 1.03 mmol) in THF (2 mL) was added to the system at −78° C. Thereaction was warmed to room temperature and stirred for 30 min. Thereaction was quenched with a saturated aqueous NH₄Cl solution at roomtemperature and extracted with EA (10 mL×2). The combined organic phaseswere washed with brine (10 mL×2), dried over Na₂SO₄ and concentratedunder reduced pressure. The residue was purified by columnchromatography to obtain the title compound (270 mg, yield: 65%). MS:M/e 733 (M+1)⁺.

Step B:(S)-(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)((1R,5S,6r)-3-azabicyclo[3.1.0]hex-6-yl)methanol

Tert-butyl(1R,5S,6r)-6-((S)-(4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-3-azabicyclo[3.1.0]hexan-3-carboxylate(270 mg, 0.37 mmol) in TFA/H₂O (9:1, 5 mL) was stirred at roomtemperature for 20 h. The reaction mixture was concentrated underreduced pressure. 10 mL of H₂O was added. The mixture was stirred atroom temperature for 10 min and then filtered. The filtrate wasextracted with DCM (5 mL×2) to remove impurities. The aqueous layer wasalkalized with an aqueous NaOH (4 M) solution to pH>10, and extractedwith DCM/IPA (5:1, 5 mL×3). The combined extracts were washed with brine(5 mL×3), dried over Na₂SO₄ and concentrated to obtain the title product(35 mg, yield: 26%). MS. M/e 333 (M+1)⁺.

Step C:7-(((1R,5S,6s)-3-azabicyclo[3.1.0]hex-6-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of(S)-(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)((1R,5S,6r)-3-azabicyclo[3.1.0]hex-6-yl)methanol(35 mg, 0.1 mmol), TFA (5 mL) and Et₃SiH (5 mL) was stirred at 60° C.for 16 h. The reaction mixture was concentrated under reduced pressure.The residue was dissolved in H₂O (2.5 mL) and extracted with DCM (2mL×3). The organic phase was discarded. The inorganic phase wasalkalinized with an aqueous NaOH (4 M) solution to pH>10. The mixturewas extracted with DCM/iPrOH (5:1, 2 mL×5). The combined organic phaseswere washed with brine (5 mL×2), dried over Na₂SO₄ and concentrated. Theresidue was purified by preparative TLC (DCM/MeOH (NH₃)=10:1) to obtainthe title compound (12 mg, yield: 36%). ¹H NMR (400 MHz, CD₃OD) δ 7.36(s, 1H), 5.19-5.01 (m, 1H), 3.22 (d, J=11.6 Hz, 2H), 3.13 (d, J=11.6 Hz,2H), 2.85 (d, J=6.8 Hz, 2H), 1.86-1.66 (m, 3H), 1.65-1.54 (m, 1H),1.54-1.38 (m, 2H), 1.35 (d, J=6.0 Hz, 3H), 1.18-1.05 (m, 1H), 0.96 (t,J=7.2 Hz, 3H) ppm. MS: Me 317 (M+1)⁺.

Step B34:2-((4-amino-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-2-yl)oxy)pentan-1-ol

Step A: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-((1-(tert-butyldimethylsilyl)oxy)pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

At −78° C. under N₂, to a solution of7-bromo-2-((1-((tert-butyldimethylsilyl)oxy)pent-2-yl)oxy)-N,N-bis(2,4-dimethoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(980 mg, 1.34 mmol) in THF (20 mL), n-BuLi (2.5 mL, 4.0 mmol) was added.After the mixture was stirred at −78° C. for 0.5 h, tert-butyl4-formylpiperidin-1-carboxylate (428 mg, 2.01 mmol) was added. Thereaction mixture was stirred at −78° C. for 2.5 h. After completion ofthe reaction, the reaction mixture was quenched with an aqueous NH₄Clsolution (30 mL) and extracted with DCM (3×50 mL). The combined organiclayers were dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by column chromatography on silica geleluted with ethyl acetate (60%) in petroleum ether to obtain the titlecompound (1 g, 86%). MS: M/e 865 (M+1)⁺.

Step B:2-((4-amino-7-(hydroxy(piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-2-yl)oxy)pentan-1-ol

Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-((1-(tert-butyldimethylsilyl)oxy)pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate(1 g, 1.156 mmol) was dissolved in TFA (9 mL) and H₂O (1 mL) under N₂.The reaction mixture was stirred at 40° C. for 12 h. After completion ofthe reaction, the solvent was removed under vacuum. The residue wasdiluted with water (20 mL) and DCM (20 mL), and the aqueous phase wasacidified with 1 N HCl to adjust pH=2-3. The aqueous phase was washedwith DCM (3×50 mL), alkalized with 2 N NaOH to adjust pH=13-14, andextracted with DCM/i-PrOH (5/1, 3×100 mL). The combined organic layerswere dried over Na₂SO₄ and concentrated under vacuum to obtain the titlecompound (350 mg, 86%). MS: M/e 351 (M+1)⁺.

Step C:2-((4-amino-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-2-yl)oxy)pentan-1-ol

2-((4-amino-7-(hydroxy(piperidin-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-2-yl)oxy)pentan-1-ol(350 mg, 1.0 mmol) was dissolved in TFA (5 mL) and Et₃SiH (5 mL) underN₂. The reaction mixture was stirred at 90° C. for 12 h. Aftercompletion of the reaction, the solvent was removed under vacuum. Theresidue was diluted with water (10 mL) and DCM (20 mL), and the aqueousphase was acidified with 1 N HCl to adjust pH=2-3. The aqueous phase waswashed with DCM (3×50 mL), alkalized with 2 N NaOH to adjust PH=13-14,and extracted with DCM/i-PrOH (5/1, 3×60 mL). The combined organiclayers were dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by preparative TLC (DCM/CH₃OH(NH₃)=10/1) to obtain the title compound (10 mg). ¹H NMR (400 MHz,CD₃OD) δ 7.43 (s, 1H), 5.15-5.08 (m, 1H), 3.75-3.71 (m, 2H), 3.38 (d,J=12.0 Hz, 2H), 3.00-2.85 (m, 4H), 2.22-2.09 (m, 1H), 1.98-1.85 (m, 2H),1.78-1.65 (m, 2H), 1.55-1.38 (m, 4H), 0.97 (t, J=7.2 Hz, 3H) ppm. MS:M/e 335 (M+1)⁺.

Compound B35:(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylidenemethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(S)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triaz-in-7-yl)methylene)piperidin-1-carboxylate

A mixture of(S)-7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(200 mg, 0.33 mmol), tert-butyl4-((4,4,5,5-tetramethyl-1,3,2-dioxboran-2-yl)methylene)piperidin-1-carboxylate(215 mg, 0.67 mmol), Pd(PPh₃)₄ (38 mg, 0.03 mmol), K₂CO₃ (93 mg, 0.67mmol) and H₂O (0.5 mL) in dioxane (2 mL) was stirred at 100° C. for 16h. The mixture was diluted with EA (10 mL), washed with brine (10 mL×3),dried over Na₂SO₄ and concentrated. The residue was purified bypreparative TLC to obtain the title compound (100 mg, yield: 42%). MS:We 717 (M+1)⁺.

Step B:(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylidenemethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Tert-butyl(S)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methylene)piperidin-1-carboxylate(100 mg, 0.14 mmol) in TFA/H₂O (9:1, 5 mL) was stirred at roomtemperature for 16 h. The reaction mixture was concentrated underreduced pressure. 5 mL of H₂O was added. The mixture was stirred at roomtemperature for 2 h and then filtered. The filtrate was alkalized withan aqueous NaOH (4 M) solution to pH>10, and extracted with DCM/IPA(5.1, 5 mL×5). The combined extracts were washed with brine (10 mL×3),dried over Na₂SO₄ and concentrated. The crude product was purified bypreparative TLC (DCM/MeOH (NH₃)=10:1) to obtain the title product (12mg, yield: 27%). ¹H NMR (400 MHz, CD₃OD) δ 7.55 (s, 1H), 6.48 (s, 1H),5.23-5.04 (m, 1H), 3.11 (t, J=6.0 Hz, 2H), 3.06 (t, J=6.0 Hz, 2H), 2.72(t, J=5.6 Hz, 2H), 2.58 (t, J=5.6 Hz, 2H), 1.85-1.67 (m, 1H), 1.67-1.54(m, 1H), 1.54-1.38 (m, 2H), 1.35 (d, J=6.0 Hz, 3H), 0.96 (t, J=7.2 Hz,3H) ppm. MS: M/e 317 (M+1)⁺.

Step B36:2-(pent-2-yloxy)-7-((tetrahydro-2H-pyran-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:(4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(tetrahydro-2H-pyran-4-yl)methanol

At −78° C. under N₂, to a solution ofN,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(500 mg, 0.959 mmol) in THF (10 mL), n-BuLi (1.8 mL, 2.88 mmol) wasadded. After the mixture was stirred at −78° C. for 0.5 h,tetrahydro-2H-pyran-4-formaldehyde (164 mg, 1.439 mmol) was added. Thereaction mixture was stirred at −78° C. for 2.5 h. After completion ofthe reaction, the reaction mixture was quenched with an aqueous NH₄Clsolution (30 mL) and extracted with DCM (3×30 mL). The combined organiclayers were dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by column chromatography on silica geleluted with ethyl acetate (60%) in petroleum ether to obtain the titlecompound (400 mg, 66%). MS: M/e 636 (M+1)⁺.

Step B:(4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(tetrahydro-2H-pyran-4-yl)methanol

(4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(tetrahydro-2H-pyran-4-yl)methanol(400 mg, 0.629 mmol) was dissolved in TFA (8 mL) and H₂O (0.8 mL) underN₂. The reaction mixture was stirred at 35° C. for 12 h. Aftercompletion of the reaction, the solvent was removed under vacuum. Theresidue was diluted with water (20 mL) and DCM (20 mL), and the aqueousphase was extracted with DCM (3×20 mL). The combined organic layers weredried over Na₂SO₄ and concentrated under vacuum to obtain a residue. Theresidue was purified by column chromatography on silica gel eluted withmethanol (NH₃) in dichloromethane (10%) to obtain the title compound(180 mg, 85%). MS: M/e 335 (M+1)⁺.

Step C:2-(pent-2-yloxy)-7-((tetrahydro-2H-pyran-4-yl)methyl)imidazo[2,1-f][1,2,4]triazin-4-amine

(4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(tetrahydro-2H-pyran-4-yl)methanol(180 mg, 0.537) was dissolved in TFA (5 mL) and Et₃SiH (5 mL) under N₂.The reaction mixture was stirred at 90° C. for 12 h. After completion ofthe reaction, the solvent was removed under vacuum. The residue wasdiluted with an aqueous NaHCO₃ solution (20 mL) and DCM (20 mL), and theaqueous phase was extracted with DCM (3×20 mL). The combined organiclayers were dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by preparative TLC (PE/EtOAc=2/1) toobtain the title compound (70 mg, 41%). ¹H NMR (400 MHz, DMSO-d₆) δ8.17-7.89 (m, 2H), 7.30 (s, 1H), 5.04-4.98 (m, 1H), 3.81 (d, J=9.2 Hz,2H), 3.23 (t, J=11.6 Hz, 2H), 2.73 (d, J=6.8 Hz, 2H), 1.94 (s, 1H),1.76-1.61 (m, 1H), 1.59-1.44 (m, 3H), 1.42-1.31 (m, 2H), 1.31-1.16 (m,5H), 0.91 (t, J=7.2 Hz, 3H) ppm. MS: Me 320 (M+1)⁺.

Compound B37:(S)-2-(pent-2-yloxy)-N7-(piperidin-4-yl)imidazo[2,1-f][1,2,4]triazin-4,7-diamine

Step A: Tert-butyl(S)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)amino)piperidin-1-carboxylate

To a solution of(S)-7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(300 mg, 0.5 mmol) in toluene (10 mL), tert-butyl4-aminopiperidin-1-carboxylate (200 mg, 1 mmol), Pd₂(dba)₃ (23 mg, 0.025mmol), t-BuONa (96 mg, 1 mmol) and BINAP (600 mg, 1 mmol) were added.The reaction mixture was stirred at 100° C. overnight under theprotection of N₂ atmosphere. H₂O was added, and the mixture wasextracted with ethyl acetate. The combined organic extracts were driedover sodium sulfate, filtered and evaporated. The crude product waspurified by column chromatography to obtain the title product (160 mg,44.4%). MS: m/e: 720 (M+1)⁺.

Step B:(S)-2-(pent-2-yloxy)-N7-(piperidin-4-yl)imidazo[2,1-f][1,2,4]triazin-4,7-diamine

H₂O (2 mL) was added to a mixture of tert-butyl(S)-4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)amino)piperidin-1-carboxylate(160 mg, 0.22 mmol) in TFA (8 mL). The resulting mixture was stirred atroom temperature for 2 d, and concentrated to dryness. The residue waspurified by preparative HPLC to obtain the target compound (17 mg,34.8%). ¹H NMR (400 MHz, DMSO-d6) δ 8.72 (s, 1H), 8.49 (s, 1H), 7.88 (s,2H), 6.90 (s, 1H), 5.45 (s, 1H), 5.05 (dd, J=12.3, 5.9 Hz, 1H), 3.48 (s,2H), 2.95 (m, 2H), 2.06 (d, J=13.4 Hz, 2H), 1.70 (m, 2H), 1.63-1.48 (m,2H), 1.37 (dt, J=15.6, 7.7 Hz, 2H), 1.25 (d, J=6.1 Hz, 3H), 0.90 (t,J=7.2 Hz, 3H) ppm. MS: Me 320 (M+1)⁺.

Compound B38:(S)-7-((1-(2-aminomethyl)piperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(S)-(2-(4-((4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)ethyl)carbamate

At room temperature, to a mixture of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-anime(50 mg, 0.16 mmol), tert-butyl (2-oxoethyl)carbamate (50 mg, 0.31 mmol)in MeOH (2 mL), NaBH₃CN (20 mg, 0.31 mmol) was added, and the mixturewas stirred for 16 h. The mixture was concentrated and diluted with DCM(10 mL), washed with brine (10 mL×3), dried over Na₂SO₄ and concentratedunder reduced pressure. The residue was purified by preparative TLC(DCM/MeOH (NH₃)=10:1) to obtain the title compound (45 mg, yield: 63%).MS: M/e 462 (M+1)⁺.

Step B:(S)-7-((1-(2-aminomethyl)piperidin-4-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

TFA (2 mL) was added to a solution of tert-butyl(S)-2-(4-((4-amino-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)ethyl)carbamate(45 mg, 0.1 mmol) in DCM (5 mL), and the solution was stirred at roomtemperature for 16 h. The reaction mixture was concentrated underreduced pressure. The resulting residue was treated with 5 mL of NaHCO₃solution. The resulting mixture was extracted with DCM/IPA (5:1, 5mL×3). The combined extracts were washed with brine (5 mL×2), dried overNa₂SO₄ and concentrated. The crude product was purified by preparativeTLC (DCM/MeOH (NH₃)=7:1) to obtain the title product (8 mg, yield: 22%).¹H NMR (400 MHz, CD₃OD) δ 7.32 (s, 1H), 5.18-5.03 (m, 1H), 3.28-2.97 (m,4H), 3.00-2.76 (m, 4H), 2.63-2.13 (m, 2H), 2.04-1.88 (m, 1H), 1.88-1.68(m, 3H), 1.66-1.40 (m, 5H), 1.36 (d, J=6.0 Hz, 3H), 0.97 (t, J=7.2 Hz,3H) ppm. MS: M/e 362 (M+1)⁺.

Compound B39:(S)-7-(azetidin-3-ylmethyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl3-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)azetidin-1-carboxylate

At −78° C. under N₂ atmosphere, to a solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(300 mg, 0.57 mmol) in THF (3 mL). n-BuLi (1.6 M, 1.1 mL, 1.72 mmol) wasadded. The mixture was stirred at −78° C. for 30 min. Then, a solutionof tert-butyl 3-formylpiperidin-1-carboxylate (320 mg, 1.72 mmol) in THF(3 mL) was added to the system at −78° C. The reaction was warmed toroom temperature and stirred for 30 min. The reaction was quenched witha saturated aqueous NH₄Cl solution at room temperature and extractedwith EA (10 mL×2). The combined organic phases were washed with brine(10 mL×3), dried over Na₂SO₄ and concentrated under reduced pressure.The residue was purified by column chromatography to obtain the titlecompound (420 mg, yield: >90%). MS: M/e 707 (M+1)⁺.

Step B:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(azetidin-3-yl)methanol

Tert-butyl3-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)azetidin-1-carboxylate(420 mg, 0.57 mmol) in TFA/H₂O (9:1, 5 mL) was stirred at 40° C. for 20h. The reaction mixture was concentrated under reduced pressure. 10 mLof H₂O was added. The mixture was stirred at room temperature for 10 minand then filtered. The filtrate was extracted with DCM (5 mL×2) toremove impurities. The aqueous layer was alkalized with an aqueous NaOH(4 M) solution to pH>10, and extracted with DCM/IPA (5:1, 5 mL×3). Thecombined extracts were washed with brine (10 mL×2), dried over Na₂SO₄and concentrated to obtain the title product (160 mg, yield: 88%). MS:M/e 307 (M+1)⁺.

Step C:(S)-7-(azetidin-3-ylmethyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

A mixture of(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(azetidin-3-yl)methanol(160 mg, 0.52 mmol), TFA (5 mL) and Et₃SiH (5 mL) was stirred at 70° C.for 16 h. Additional TFA (5 mL) and Et₃SiH (5 mL) were added, and theresulting mixture was stirred at 70° C. for 2 d. The reaction mixturewas concentrated under reduced pressure. The residue was treated withH₂O (10 mL) and alkalized with an aqueous NaOH solution (4 M) to pH>10.The mixture was extracted with DCM/iPrOH (5:1, 10 mL×3). The combinedorganic phases were washed with brine (10 mL×2), dried over Na₂SO₄ andconcentrated. The residue was purified by preparative TLC (DCM/MeOH(NH₃)=10:1) to obtain the title compound (12 mg, yield: 8%). ¹H NMR (400MHz, CD₃OD) δ 7.37 (s, 1H), 5.20-5.04 (m, 1H), 4.15 (t, J=9.6 Hz, 2H),4.02-3.90 (m, 2H), 3.48-3.35 (m, 1H), 3.22 (d, J=7.2 Hz, 2H), 1.87-1.67(m, 1H), 1.67-1.56 (m, 1H), 1.55-1.40 (m, 2H), 1.36 (d, J=6.0 Hz, 3H),0.96 (t, J=7.2 Hz, 3H) ppm. MS: M/e 291 (M+1)⁺.

Compound B40:(S)-7-((3-aminobicyclo[1.1.1]pent-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(3-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)bicyclo[1.1.1]pent-1-yl)carbamate

To a solution of(S)-7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(450 mg, 0.75 mmol) in THF (10 mL), a solution of n-BuLi (1.6 M, 0.94mL, 1.5 mmol) was added dropwise at a temperature of −75° C. to −65° C.One hour later, a suspension of tert-butyl(3-formylbicyclo[1.1.1]pent-h-yl)carbamate (317 mg, 1.5 mmol) in THF (3mL) was added dropwise. The resulting mixture was stirred at −70° C. for3 h and then warmed to room temperature. The reaction was quenched witha saturated NH₄Cl solution, extracted with EtOAc (20 mL×3), washed withbrine, dried over Na₂SO₄, filtered and concentrated. The residue waspurified by preparative TLC to obtain the target compound (130 mg,yellow oil, yield 23.6%). MS: M/e 733 (M+1)⁺.

Step B:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(3-aminobicyclo[1.1.1]pent-1-yl)methanol

H₂O (1 mL) was added to a mixture of the product of step A (130 mg,crude) in TFA (4.5 mL), and the resulting mixture was stirred at 40° C.for 12 h. The mixture was cooled to room temperature and concentrated todryness. H₂O (15 mL) was added to the residue, and the mixture wasextracted with DCM (15 mL×2). The aqueous phase was alkalized with 2 NNaOH to pH=12-13, extracted with a DCM/iPrOH (4:1) mixture (20 mL×2),dried over Na₂SO₄, filtered and concentrated. The residue (30 mg) wasused directly without further purification. MS: M/e 333 (M+1)⁺.

Step C:(S)-7-((3-aminobicyclo[1.1.1]pent-1-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (3 mL) was added to a mixture of the product of step B (30 mg,crude) in TFA (3 mL), and the resulting mixture was stirred at 70° C.for 12 h. The mixture was cooled to room temperature and concentrated todryness. H₂O (15 mL) was added to the residue and the mixture wasextracted with DCM (15 mL×2). The aqueous phase was alkalized with 2 NNaOH to pH=12-13, extracted with a DCM/iPrOH (4:1) mixture (20 mL×2),dried over Na₂SO₄, filtered and concentrated. The residue was purifiedby preparative TLC to obtain the target compound (13.5 mg, 24% for twosteps). 1H NMR (400 MHz, DMSO-d6) δ 8.13 (s, 1H), 8.04 (s, 1H), 7.33 (s,1H), 5.02 (dd, J=12.2, 6.1 Hz, 1H), 3.10 (s, 2H), 1.69 (d, J=11.8 Hz,8H), 1.59 (dt, J=13.4, 6.3 Hz, 1H), 1.44 (dt, J=14.8, 6.9 Hz, 2H), 1.33(d, J=6.1 Hz, 3H), 0.96 (t, J=7.3 Hz, 3H) ppm. MS: We 317 (M+1)⁺.

Compound B41:2-((5-methylisoxazol-3-yl)methoxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-((5-methylisoxazol-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-4-amine

NaH (60%, 80 mg, 2 mmol) was added to a solution of(5-methylisoxazol-3-yl)methanol (113 mg, 1 mmol) in THF (10 mL) at 0° C.The reaction mixture was stirred at room temperature for 20 min.7-bromo-2-chloro-N,N-bis(2,4-dimethoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(300 mg, 0.5 mmol) was added to the mixture. The reaction mixture wasstirred at room temperature for 20 min. An aqueous ammonium chloridesolution was added and the mixture was extracted with ethyl acetate. Thecombined organic extracts were dried over sodium sulfate, filtered andevaporated. The crude product was purified by column chromatography toobtain the title product (200 mg, 64.1%). MS: M/e: 624.7 (M+1)⁺.

Step B: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-((5-methylisoxazol-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-((5-methylisoxazol-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-4-amine(200 mg, 0.32 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 0.3 mL,0.48 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl4-formyl-2-methylpiperidin-1-carboxylate (82 mg, 0.38 mmol) in THF (2mL) was added dropwise. The resulting mixture was stirred at −70° C. for2 h, and then warmed to room temperature to react overnight. Thereaction was quenched with a saturated NH₄Cl solution, extracted withEtOAc (20 mL×3), washed with brine, dried over Na₂SO₄, filtered andconcentrated. The residue was purified by preparative TLC to obtain thetarget compound (100 mg, 41.3%). MS: M/e 760 (M+1)⁺.

Step C:(4-amino-2-((5-methylisoxazol-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(piperidin-4-yl)methanol

To a mixture of the product of step B (100 mg, 0.131 mmol) in TFA (8mL), H₂O (2 mL) was added, and the resulting mixture was stirred at roomtemperature for 2 d. The mixture was concentrated to dryness. H₂O wasadded to the residue and the mixture was filtered. The filtrate waswashed with DCM, and adjusted to pH 12-13 with a 2 M NaOH solution. Thesolution was extracted with DCM (20 mL×3). The organic phase was washedwith brine, dried over Na₂SO₄, filtered and concentrated to obtain thetarget compound (30 mg), which was directly used in the next step. MS:M/e 360 (M+1)⁺.

Step D:2-((5-methylisoxazol-3-yl)methoxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step C (30 mg,crude) in TFA (4 mL), and the resulting mixture was stirred at 85° C.for 2 h. The mixture was cooled to room temperature and concentrated todryness. The residue was purified by preparative HPLC to obtain thetarget compound (5 mg, 11.1% for two steps). ¹H NMR (400 MHz, DMSO-d6) δ8.49 (s, 1H), 8.27 (s, 1H), 8.19 (s, 1H), 7.36 (s, 1H), 6.33 (s, 1H),5.33 (s, 2H), 3.23 (d, J=11.7 Hz, 2H), 2.77 (d, J=6.3 Hz, 2H), 2.41 (s,3H), 1.96 (s, 1H), 1.73 (m, 2H), 1.34 (m, 2H) ppm. MS: M/e 333 (M+1)⁺.

Compound B42:2-(((S)-pent-2-yl)oxy)-7-(pyrrolidin-2-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)pyrrolidin-1-carboxylate

To a solution of(S)-7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(600 mg, 1 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 1.25 mL, 2mmol) was added dropwise at a temperature of −75° C. to −65° C. One hourlater, a suspension of tert-butyl 2-formylpyrrolidin-1-carboxylate (298mg, 1.5 mmol) in THF (2 mL) was added dropwise. The resulting mixturewas stirred at −70° C. for 2 h, and then warmed to room temperature toreact overnight. The reaction was quenched with a saturated NH₄Clsolution, extracted with EtOAc (20 mL×3), washed with brine, dried overNa₂SO₄, filtered and concentrated. The residue was purified bypreparative TLC to obtain the target compound (600 mg, 83.4%). MS: M/e721 (M+1)⁺.

Step B: Tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-v)(((methylthio)thiocarbonyl)oxy)methyl)pyrrolidin-1-carboxylate

At 0° C., to a solution of tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)pyrrolidin-1-carboxylate(200 mg, 0.28 mmol), carbon disulfide (32 mg, 0.42 mmol) and imidazole(20 mg, 0.3 mmol) in THF (8 mL), NaH (6(0%, 23 mg, 0.56 mmol) was added,and the mixture was stirred for 30 min. To this mixture, methyl iodide(80 mg, 0.56 mmol) was added, and then the mixture was stirred at 0° C.for 1.5 h and at room temperature for 3.5 h. The reaction was quenchedwith a saturated NH₄Cl solution, extracted with EtOAc (20 mL×3), washedwith brine, dried over Na₂SO₄, filtered and concentrated. The residuewas purified by preparative TLC to obtain the target compound (160 mg,70.7%). MS: M/e 811 (M+1)⁺.

Step C: Tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)pyrrolidin-1-carboxylate

To a mixture of tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(((methylthio)thiocarbonyl)oxy)methyl)pyrrolidin-1-carboxylate(90 mg, 0.111 mmol) in toluene (10 mL), tributyltin hydride (65 mg, 0.22mmol) and AIBN (18 mg, 0.11 mmol) were added. The resulting mixture wasstirred at 100° C. overnight under the protection of nitrogenatmosphere, and then concentrated and dried. The residue was added towater, extracted with EtOAc (20 mL×3), washed with brine, dried overNa₂SO₄, filtered and concentrated. The residue was purified bypreparative TLC to obtain the target compound (60 mg, 77.9%). MS: M/e705 (M+1)⁺.

Step D:2-(((S)-pent-2-yl)oxy)-7-(pyrrolidin-2-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

To a mixture of the product of step C (60 mg, 0.085 mmol) in TFA (8 mL),H₂O (2 mL) was added, and then the mixture was stirred at roomtemperature for 2 d. The mixture was concentrated to dryness. Theresidue was purified by preparative HPLC to obtain the target compound(9 mg, 34.6%). ¹H NMR (400 MHz, DMSO-d6) δ 8.74 (s, 1H), 8.21 (s, 1H),8.10 (s, 1H), 7.44 (s, 1H), 5.02 (dd, J=12.0, 6.0 Hz, 1H), 3.85 (s, 1H),3.28-3.18 (m, 3H), 3.16 (d, J=6.6 Hz, 1H), 2.08 (d, J=6.7 Hz, 1H), 1.97(d, J=5.4 Hz, 1H), 1.89 (d, J=7.1 Hz, 1H), 1.73-1.61 (m, 2H), 1.54 (d,J=6.3 Hz, 1H), 1.38 (dt, J=15.5, 7.9 Hz, 2H), 1.28 (d, J=6.0 Hz, 3H),0.90 (dd, J=15.4, 8.0 Hz, 3H) ppm. MS: M/e 305 (M+1)⁺.

Compound B43:(S)-7-((2-azaspiro[3.5]non-7-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl7-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-2-azaspiro[3.5]nonan-2-carboxylate

To a solution of(S)-7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(330 mg, 0.55 mmol) in THF (10 mL), a solution of n-BuLi (1.6 M, 0.69mL, 1.1 mmol) was added dropwise at a temperature of −75° C. to −65° C.One hour later, a suspension of tert-butyl7-formyl-2-azaspiro[3.5]nonan-2-carboxylate (209 mg, 0.82 mmol) in THF(3 mL) was added dropwise. The resulting mixture was stirred at −70° C.for 3 h and then warmed to room temperature. The reaction was quenchedwith a saturated NH₄Cl solution, extracted with EtOAc (20 mL×3), washedwith brine, dried over Na₂SO₄, filtered and concentrated. The residuewas purified by preparative TLC to obtain the target compound (200 mg,yellow oil, yield 47%). MS: M/e 775 (M+1)⁺.

Step B:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(2-azaspiro[3.5]non-7-yl)methanol

H₂O (1 mL) was added to a mixture of the product of step A (200 mg,crude) in TFA (4.5 mL), and the resulting mixture was stirred at 40° C.for 12 h. The mixture was cooled to room temperature and concentrated todryness. H₂O (15 mL) was added to the residue and the mixture wasextracted with DCM (15 mL×2). The aqueous phase was alkalized to pH12-13 with 2 N NaOH, extracted with DCM/iPrOH=4:1 (20 mL×2), dried overNa₂SO₄, filtered and concentrated. The residue (65 mg) was used directlywithout further purification. MS: M/e 375 (M+1)⁺.

Step C:(S)-7-((2-azaspiro[3.5]non7-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step B (65 mg,crude) in TFA (4 mL), and the residue was stirred at 70° C. for 12 h.The mixture was cooled to room temperature and concentrated to dryness.H₂O (15 mL) was added to the residue and the mixture was extracted withDCM (15 mL×2). The aqueous phase was alkalized to pH 12-13 with 2 NNaOH, extracted with DCM/iPrOH=4:1 (20 mL×2), dried over Na₂SO₄,filtered and concentrated. The residue was purified by preparative HPLCto obtain the target compound (8.3 mg, 10% for two steps). ¹H NMR (400MHz, DMSO-d6) δ 8.38 (s, 1H), 8.05 (s, 1H), 7.96 (s, 1H), 7.27 (s, 1H),4.96 (m, 1H), 3.58 (s, 2H), 3.50 (s, 3H), 2.65 (d, J=6.8 Hz, 2H), 1.95(d, J=12.7 Hz, 2H), 1.66 (d, J=6.2 Hz, 2H), 1.55 (d, J=9.3 Hz, 3H), 1.35(d, J=12.8 Hz, 4H), 1.27 (d, J=6.0 Hz, 3H), 0.99 (m, 2H), 0.90 (t, J=7.2Hz, 3H) ppm. MS: M/e 359 (M+1)⁺.

Compound B44:2-((5-methylthiazol-2-yl)methoxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-((5-methylthiazol-2-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-4-amine

NaH (60%, 80 mg, 2 mmol) was added to a solution of(5-methylthiazol-2-yl)methanol (129 mg, 1 mmol) in THF (10 mL) at 0° C.The reaction mixture was stirred at room temperature for 20 min.7-bromo-2-chloro-N,N-bis(2,4-dimethoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(300 mg, 0.5 mmol) was added to the mixture. The reaction mixture wasstirred at 70° C. overnight. An aqueous ammonium chloride solution wasadded and the mixture was extracted with ethyl acetate. The combinedorganic extracts were dried over sodium sulfate, filtered andevaporated. The crude product was purified by column chromatography toobtain the title product (240 mg, 75%). MS: M/e: 642 (M+1)⁺.

Step B: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-((5-methylthiazol-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-((5-methylthiazol-2-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-4-amine(240 mg, 0.38 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 0.35 mL,0.56 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl4-formyl-2-methylpiperidin-1-carboxylate (95 mg, 0.45 mmol) in THF (2mL) was added dropwise. The resulting mixture was stirred at −70° C. for2 h, and then warmed to room temperature to react overnight. Thereaction was quenched with a saturated NH₄Cl solution, extracted withEtOAc (20 mL×3), washed with brine, dried over Na₂SO₄, filtered andconcentrated. The residue was purified by preparative TLC to obtain thetarget compound (110 mg, 37.8%). MS: We 777 (M+1)⁺.

Step C:(4-amino-2-((5-methylthiazol-2-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(piperidin-4-yl)methanol

H₂O (2 mL) was added to a mixture of the product of step B (110 mg,0.141 mmol) in TFA (8 mL), and the resulting mixture was stirred at roomtemperature for 2 d. The mixture was concentrated to dryness. H₂O wasadded to the residue and the mixture was filtered. The filtrate waswashed with DCM, and adjusted to pH 12-13 with 2 M NaOH solution. Thesolution was extracted with DCM (20 mL×3). The organic phase was washedwith brine, dried over Na₂SO₄, filtered and concentrated to obtain thetarget compound (30 mg), which was directly used in the next step. MS:M/e 376 (M+1)⁺.

Step D:2-((5-methylthiazol-2-yl)methoxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step C (30 mg,crude) in TFA (4 mL), and the resulting mixture was stirred at 80° C.for 2 h. The mixture was cooled to room temperature and concentrated todryness. The residue was purified by preparative HPLC to obtain thetarget compound (5 mg, 9.8% for two steps). ¹H NMR (400 MHz, DMSO-d6)) δ8.34 (s, 1H), 8.28 (s, 1H), 7.50 (s, 1H), 7.39 (d, J=5.6 Hz, 1H), 7.23(s, 1H), 5.52 (s, 2H), 3.21 (d, J=12.5 Hz, 2H), 2.79 (d, J=6.4 Hz, 4H),2.43 (s, 3H), 1.99 (s, 1H), 1.75 (d, J=5.3 Hz, 1H), 1.71 (s, 1H), 1.39(s, 2H) ppm. MS: M/e 360 (M+1)⁺.

Compound B45:2-((1-phenylpent-2-yl)oxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: 1-phenylpentan-2-ol

Ethyl magnesium bromide (2 M, 7 mL, 14 mmol) was added to a solution of2-phenylacetaldehyde (1.2 g, 10 mmol) in THF (10 mL) at 0° C. Thereaction mixture was stirred at room temperature for 2 h. Water wasadded to the mixture and the resulting mixture was extracted with ethylacetate. The combined organic extracts were dried over sodium sulfate,filtered and evaporated. The crude product was purified by columnchromatography to obtain the title product (520 mg, 31.7%). MS: M/e: 165(M+1)⁺.

Step B:7-bromo-N,N-bis(4-methoxybenzyl)-2-((1-phenylpent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

NaH (60%, 80 mg, 2 mmol) was added to a solution of 1-phenylpentan-2-ol(169 mg, 1 mmol) in THF (10 mL) at 0° C., and the reaction mixture wasstirred at room temperature for 20 min.7-bromo-2-chloro-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(243 mg, 0.5 mmol) was added to the mixture. The reaction mixture wasstirred at 70° C. overnight. An aqueous ammonium chloride solution wasadded and the mixture was extracted with ethyl acetate. The combinedorganic extracts were dried over sodium sulfate, filtered andevaporated. The crude product was purified by column chromatography toobtain the title product (220 mg, 81.9%). MS: M/e: 616 (M+1)⁺.

Step C: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-((1-phenylpent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of7-bromo-N,N-bis(4-methoxybenzyl)-2-((1-phenylpent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine(220 mg, 0.36 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 0.45 mL,0.72 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl4-formyl-2-methylpiperidin-1-carboxylate (115 mg, 0.54 mmol) in THF (2mL) was added dropwise. The resulting mixture was stirred at −70° C. for2 h, and then warmed to room temperature to react overnight. Thereaction was quenched with a saturated NH₄Cl solution, extracted withEtOAc (20 mL×3), washed with brine, dried over Na₂SO₄, filtered andconcentrated. The residue was purified by preparative TLC to obtain thetarget compound (140 mg, 51.8%). MS: We 752 (M+1)⁺.

Step D:2-((1-phenylpent-2-yl)oxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step C (140 mg,0.186 mmol) in TFA (4 mL), and the resulting mixture was stirred at 85°C. for 4 h. The mixture was cooled to room temperature and concentratedto dryness. TFA (5 mL) was added to the residue, and then the reactionmixture was heated at 80° C. overnight. The mixture was concentrated andthe residue was purified by preparative HPLC to obtain the targetcompound (4 mg, 15% for two steps). 1H NMR (400 MHz, DMSO-d6) δ 8.09 (s,1H), 8.02 (s, 1H), 7.33-7.25 (m, 5H), 7.20 (d, J=3.2 Hz, 1H), 5.11 (s,1H), 3.06 (d, J=12.3 Hz, 3H), 2.89-2.83 (m, 1H), 2.75 (d, J=6.3 Hz, 2H),2.57 (s, 2H), 1.90 (s, 1H), 1.68-1.53 (m, 4H), 1.46-1.31 (m, 2H), 1.24(s, 2H), 0.86 (t, J=7.0 Hz, 3H) ppm. MS: Me 395 (M+1)⁺.

Compound B46:7-(piperidin-4-ylmethyl)-2-((tetrahydrofuran-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:7-bromo-N,N-bis(4-methoxybenzyl)-2-((tetrahydrofuran-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-4-amine

NaH (60%, 160 mg, 4 mmol was added to a solution of(tetrahydrofuran-3-yl)methanol (204 mg, 2 mmol) in THF (10 mL) at 0° C.The reaction mixture was stirred at room temperature for 20 min.7-bromo-2-chloro-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(487 mg, 1 mmol) was added to the mixture. The reaction mixture wasstirred at 70° C. overnight. An aqueous ammonium chloride solution wasadded and the mixture was extracted with ethyl acetate. The combinedorganic extracts were dried over sodium sulfate, filtered andevaporated. The crude product was purified by column chromatography toobtain the title product (500 mg, 90%). MS: M/e: 554 (M+1)⁺.

Step B: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-((tetrahydrofuran-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of7-bromo-N,N-bis(4-methoxybenzyl)-2-((tetrahydrofuran-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-4-amine(220 mg, 0.39 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 0.45 mL,0.72 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl4-formyl-2-methylpiperidin-1-carboxylate (115 mg, 0.54 mmol) in THF (2mL) was added dropwise. The resulting mixture was stirred at −70° C. for2 h, and then warmed to room temperature to react overnight. Thereaction was quenched with a saturated NH₄Cl solution, extracted withEtOAc (20 mL×3), washed with brine, dried over Na₂SO₄, filtered andconcentrated. The residue was purified by preparative TLC to obtain thetarget compound (130 mg, 47.6%). MS: M/e 689 (M+1).

Step C:7-(piperidin-4-ylmethyl)-2-((tetrahydrofuran-3-yl)methoxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step B (130 mg,0.33 mmol) in TFA (4 mL), and the resulting mixture was stirred at 85°C. for 4 h. The mixture was cooled to room temperature and concentratedto dryness. TFA (5 mL) was added to the residue, and the reactionmixture was heated at 80° C. overnight. The mixture was concentrated,and the residue was purified by preparative HPLC to obtain the targetcompound (18 mg, 16.3%). 1H NMR (400 MHz, DMSO-d6) δ 8.13 (s, 1H), 8.03(s, 1H), 7.30 (s, 1H), 4.19 (d, J=6.8 Hz, 1H), 4.15-4.07 (m, 1H), 3.77(dd, J=16.7, 8.5 Hz, 2H), 3.65 (d, J=7.6 Hz, 1H), 3.55-3.48 (m, 1H),2.96 (d, J=12.1 Hz, 2H), 2.71 (d, J=6.6 Hz, 2H), 2.69-2.63 (m, 1H), 2.45(s, 2H), 2.00 (s, 1H), 1.80 (s, 1H), 1.65 (dd, J=12.1, 6.1 Hz, 1H), 1.56(d, J=12.6 Hz, 2H), 1.13 (d, J=11.4 Hz, 2H) ppm. MS: M/e 333 (M+1)⁺.

Compound B47:2-(hept-4-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-(hept-4-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of2-(hept-4-yloxy)-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(160 mg, 0.327 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 0.31mL, 0.5 mmol) was added dropwise at a temperature of −75° C. to −65° C.One hour later, a suspension of tert-butyl4-formylpiperidin-1-carboxylate (98 mg, 0.46 mmol) in THF (2 mL) wasadded dropwise. The resulting mixture was stirred at −70° C. for 2 h,and then warmed to room temperature to react overnight. The reaction wasquenched with a saturated NH₄Cl solution, extracted with EtOAc (20mL×3), washed with brine, dried over Na₂SO₄, filtered and concentrated.The residue was purified by preparative TLC to obtain the targetcompound (120 mg, 52.4%). MS: M/e 703 (M+1)⁺.

Step B:2-(hept-4-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step A (120 mg,0.17 mmol) in TFA (4 mL), and the resulting mixture was stirred at 85°C. for 4 h. The mixture was cooled to room temperature and concentratedto dryness. TFA (5 mL) was added to the residue, and the reactionmixture was stirred at 80° C. overnight. The mixture was concentratedunder vacuum, and the residue was purified by preparative HPLC to obtainthe target compound (6 mg, 10.2%). 1H NMR (400 MHz, DMSO-d6) δ 8.07 (s,1H), 7.97 (s, 1H), 7.31 (s, 1H), 5.02-4.90 (m, 1H), 3.12 (d, J=12.3 Hz,2H), 2.74 (d, J=6.7 Hz, 2H), 2.65 (t, J=11.6 Hz, 2H), 1.89 (s, 1H),1.70-1.54 (m, 6H), 1.42-1.23 (m, 7H), 0.90 (t, J=7.3 Hz, 6H) ppm. MS: We347 (M+1)⁺.

Step B48:2-(pent-3-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-(pent-3-yloxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution ofN,N-bis(4-methoxybenzyl)-2-(pent-3-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(110 mg, 0.23 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 0.3 mL,0.48 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl 4-formylpiperidin-1-carboxylate(60 mg, 0.3 mmol) in THF (2 mL) was added dropwise. The resultingmixture was stirred at −70° C. for 2 h, and then warmed to roomtemperature to react overnight. The reaction was quenched with asaturated NH₄Cl solution, extracted with EtOAc (20 mL×3), washed withbrine, dried over Na₂SO₄, filtered and concentrated. The residue waspurified by preparative TLC to obtain the target compound (70 mg,45.2%). MS: M/e 675 (M+1)⁺.

Step B:2-(pent-3-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step A (70 mg,0.103 mmol) in TFA (4 mL), and the resulting mixture was stirred at 85°C. for 4 h. The mixture was cooled to room temperature and concentratedto dryness. TFA (5 mL) was added to the residue and the reaction mixturewas stirred at 80° C. overnight. The mixture was concentrated, and theresidue was purified by preparative HPLC to obtain the target compound(7 mg, 21.2%). 1H NMR (400 MHz, DMSO-d6) δ 8.06 (s, 1H), 7.96 (s, 1H),7.29 (s, 1H), 4.82-4.73 (m, 1H), 3.00 (d, J=12.0 Hz, 2H), 2.71 (d, J=6.7Hz, 2H), 2.54 (s, 2H), 1.84 (s, 1H), 1.69-1.53 (m, 6H), 1.23-1.11 (m,2H), 0.90 (t, J=7.3 Hz, 6H) ppm. MS: M/e 319 (M+1)⁺.

Compound B49:(S)-2-(hex-3-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A:(S)-2-(hex-3-yloxy)-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine

NaH (60%, 80 mg, 2 mmol) was added to a solution of (S)-hexan-3-ol (102mg, 1 mmol) in THF (10 mL) at 0° C. The reaction mixture was stirred atroom temperature for 20 min.2-chloro-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(204 mg, 0.5 mmol) was added to the reaction mixture. The reactionmixture was stirred at 70° C. overnight. An aqueous ammonium chloridesolution was added and the mixture was extracted with ethyl acetate. Thecombined organic extracts were dried over sodium sulfate, filtered andevaporated. The crude product was purified by column chromatography toobtain the title product (190 mg, 80%). MS: M/e: 476 (M+1)⁺.

Step B: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-(((S)-hex-3-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of(S)-2-(hexan-3-yloxy)-N,N-bis(4-methoxybenzyl)imidazo[2,1-f][1,2,4]triazin-4-amine(190 mg, 0.4 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 0.44 mL,0.72 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl 4-formylpiperidin-1-carboxylate(122 mg, 0.6 mmol) in THF (2 mL) was added dropwise. The resultingmixture was stirred at −70° C. for 2 h, and then warmed to roomtemperature to react overnight. The reaction was quenched with asaturated NH₄Cl solution, extracted with EtOAc (20 mL×3), washed withbrine, dried over Na₂SO₄, filtered and concentrated. The residue waspurified by preparative TLC to obtain the target compound (90 mg,32.7%). MS: M/e 689 (M+1)⁺.

Step C:(S)-2-(hex-3-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step B (90 mg,0.130 mmol) in TFA (4 mL), and the resulting mixture was stirred at 85°C. for 4 h. The mixture was cooled to room temperature and concentratedto dryness. TFA (5 mL) was added to the residue and the reaction mixturewas stirred at 80° C. overnight. The mixture was concentrated undervacuum, and the residue was purified by preparative HPLC to obtain thetarget compound (9 mg, 20.8%). 1H NMR (400 MHz, DMSO-d6) δ 8.06 (br.s,1H), 7.96 (s, 1H), 7.29 (s, 1H), 4.91-4.81 (m, 1H), 3.00 (d, J=11.8 Hz,2H), 2.71 (d, J=6.7 Hz, 2H), 2.54 (s, 2H), 1.83 (s, 1H), 1.72-1.51 (m,6H), 1.42-1.33 (m, 2H), 1.25-1.07 (m, 2H), 0.90 (t, J=7.3 Hz, 6H) ppm.MS: M/e 333 (M+1)⁺.

Compound B50:(S)-7-((7-azaspiro[3.5]non-2-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl 2-methylene-7-azaspiro[3.5]nonan-7-carboxylate

NaHMDS (8.4 mL, 16.8 mmol) was added to a solution of Ph₃PCH₃Br (5.98 g,16.74 mmol) in THF (30 mL) at −78° C. under N₂. After the mixture wasstirred at −78° C. for 10 min, the reaction was warmed to 25° C. andstirred for 2 h. Tert-butyl 2-oxo-7-azaspiro[3.5]nonan-7-carboxylate (2g, 8.37 mmol) in THF (10 mL) was added dropwise at 0° C. The reactionmixture was stirred at 70° C. for 5 h. After completion of the reaction,the reaction mixture was quenched with water (50 mL) and extracted withEtOAc (3×50 mL). The combined organic layers were dried over Na₂SO₄ andconcentrated under vacuum to obtain a residue. The residue was purifiedby column chromatography on silica gel eluted with ethyl acetate (25%)in petroleum ether to obtain the title compound (1.2 g, 61%). ¹H NMR(400 MHz, DMSO-d6) δ 4.84 (s, 2H), 3.26 (s, 4H), 2.41 (s, 4H), 1.53-1.43(m, 4H), 1.41 (s, 9H) ppm.

Step B. Tert-butyl 2-(hydroxymethyl)-7-azaspiro[3.5]nonan-7-carboxylate

Under N₂, 9-BBN (15 mL, 7.5 mmol) was added to a solution of tert-butyl2-methylene-7-azaspiro[3.5]nonan-7-carboxylate (1.2 g, 5.06 mmol) in THF(20 mL). After the mixture was stirred at 70° C. for 6 h, the reactionwas cooled to 0° C. and NaOH (3 N, 8 mL) and H₂O₂ (8 mL) were added. Thereaction mixture was stirred at 25° C. for 12 h. After completion of thereaction, the reaction mixture was quenched with ice water (20 mL) andextracted with DCM (3×50 mL). The combined organic layers were driedover Na₂SO₄ and concentrated under vacuum to obtain a residue. Theresidue was purified by column chromatography on silica gel eluted withethyl acetate (70%) in petroleum ether to obtain the title compound (1g, 78%). ¹H NMR (400 MHz, DMSO-d₆) δ 4.44 (t, J=5.2 Hz, 1H), 3.35 (s,2H), 3.24 (s, 2H), 3.15 (s, 2H), 2.36-2.24 (m, 1H), 1.76 (t, J=10.4 Hz,2H), 1.50-1.40 (m, 4H), 1.41-1.30 (m, 11H) ppm.

Step C: Tert-butyl 2-formyl-7-azaspiro[3.5]nonan-7-carboxylate

DMP (2 g, 4.72 mmol) was added to a solution of tert-butyl2-(hydroxymethyl)-7-azaspiro[3.5]nonan-7-carboxylate (1 g, 3.92 mmol) inDCM (20 mL) at 0° C. under N₂. The mixture was stirred at 25° C. for 3h. After completion of the reaction, the reaction mixture was quenchedwith an aqueous Na₂S₂O₃ solution (30 mL) and extracted with DCM (3×50mL). The combined organic layers were washed with an aqueous NaHCO₃solution (50 mL), dried over Na₂SO₄ and concentrated under vacuum toobtain a residue. The residue was purified by column chromatography onsilica gel eluted with ethyl acetate (50%) in petroleum ether to obtainthe title compound (660 mg, 67%). ¹H NMR (400 MHz, DMSO-d₆) δ 9.67 (s,1H), 3.25 (s, 2H), 3.17 (s, 3H), 1.98-1.85 (m, 4H), 1.56-1.46 (m, 2H),1.38 (s, 9H), 1.36-1.29 (m, 2H) ppm.

Step D: Tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-7-azaspiro[3.5]nonan-7-carboxylate

At −78° C. under N₂, to a solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(500 mg, 0.959 mmol) in THF (10 mL), n-BuLi (1.2 mL, 1.920 mmol) wasadded. After the mixture was stirred at −78° C. for 0.5 h, tert-butyl2-formyl-7-azaspiro[3.5]nonan-7-carboxylate (340 mg, 1.344 mmol) in THF(5 mL) was added. The reaction mixture was stirred at −78° C. for 2.5 h.After completion of the reaction, the reaction mixture was quenched withan aqueous NH₄Cl solution (30 mL) and extracted with DCM (3×50 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (40%) inpetroleum ether to obtain the title compound (560 mg, 75%). MS: M/e 775(M+1)⁺.

Step E:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(7-azaspiro[3.5]non-2-yl)methanol

Tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-7-azaspiro[3.5]nonan-7-carboxylate(560 mg, 0.722 mmol) was dissolved in TFA (9 mL) and H₂O (1 mL) underN₂. The reaction mixture was stirred at 40° C. for 12 h. Aftercompletion of the reaction, the solvent was removed under vacuum. Theresidue was diluted with water (20 mL) and DCM (20 mL), and the aqueousphase was acidified with 1 N HCl to adjust pH=1-2. The aqueous phase waswashed with DCM (3×20 ML), alkalized with 2 N NaOH to adjust PH=13-14,and extracted with DCM/i-PrOH (5/1, 3×100 mL). The combined organiclayers were dried over Na₂SO₄ and concentrated under vacuum to obtain acrude compound (280 mg, crude). MS: M/e 375 (M+1)⁺.

Step F.(S)-7-((7-azaspiro[3.5]non-2-yl)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine

(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(7-azaspiro[3.5]non-2-yl)methanol(280 mg, crude) was dissolved in TFA (6 mL) and Et₃SiH (6 mL) under N₂.The reaction mixture was stirred at 90° C. for 12 h. After completion ofthe reaction, the solvent was removed under vacuum. The residue wasdiluted with water (20 mL) and DCM (20 mL), and the aqueous phase wasacidified with 1 N HCl to adjust pH=1-2. The aqueous phase was washedwith DCM (3×20 mL), alkalized with 2 N NaOH to adjust pH=13-14, andextracted with DCM/i-PrOH (5/1, 3×60 mL). The combined organic layerswere dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by preparative TLC (DCM/MeOH(NH₃)=15/1) to obtain the title compound (80 mg, 31% for two steps). ¹HNMR (400 MHz, CD₃OD) δ 7.30 (s, 1H), 5.10 (d, J=6.0 Hz, 1H), 3.17-3.08(m, 2H), 3.05 (d, J=5.2 Hz, 2H), 2.98 (d, J=7.6 Hz, 2H), 2.88-2.68 (m,1H), 2.08 (t, J=10.4 Hz, 2H), 1.86 (d, J=5.2 Hz, 2H), 1.88-1.70 (m, 3H),1.71-1.54 (m, 3H), 1.53-1.40 (m, 2H), 1.36 (d, J=6.0 Hz, 3H), 0.96 (t,J=7.2 Hz, 3H) ppm. MS: We 359 (M+1)⁺.

Compound B51:2-(((S)-pent-2-yl)oxy)-7-(piperidin-2-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate

To a solution of(S)-7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(600 mg, 1 mmol) in THF (8 mL), a solution of n-BuLi (1.6 M, 1.25 mL, 2mmol) was added dropwise at a temperature of −75° C. to −65° C. One hourlater, a suspension of tert-butyl 2-formylpiperidin-1-carboxylate (319mg, 1.5 mmol) in THF (2 mL) was added dropwise. The resulting mixturewas stirred at −70° C. for 2 h, and then warmed to room temperature toreact overnight. The reaction was quenched with a saturated NH₄Clsolution, extracted with EtOAc (20 mL×3), washed with brine, dried overNa₂SO₄, filtered and concentrated. The residue was purified bypreparative TLC to obtain the target compound (590 mg, 80.3%). MS: M/e735 (M+1)⁺.

Step B: Tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(((methylthio)thiocarbonyl)oxy)methyl)piperidin-1-carboxylate

To a mixture of tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazol[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)piperidin-1-carboxylate(130 mg, 0.18 mmol), carbon disulfide (70 mg, 0.9 mmol) and imidazole(20 mg, 0.3 mmol) in THF (8 mL), NaH (60%, 23 mg, 0.56 mmol) was addedat 0° C., and the mixture was stirred 30 min. Methyl iodide (126 mg, 0.9mmol) was added to the mixture, and the mixture was stirred at 0° C. for1.5 h and at room temperature for 3.5 h. The reaction was quenched witha saturated NH₄Cl solution, extracted with EtOAc (20 mL×3), washed withbrine, dried over Na₂SO₄, filtered and concentrated. The residue waspurified by preparative TLC to obtain the target compound (50 mg,33.7%). MS: Me 825 (M+1)⁺.

Step C: Tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-carboxylate

To a mixture of tert-butyl2-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(((methylthio)thiocarbonyl)oxy)methyl)piperidin-1-carboxylate(50 mg, 0.06 mmol) in toluene (10 mL), tri-n-butyl tin hydride (65 mg,0.22 mmol) and AIBN (18 mg, 0.11 mmol) were added. The resultingreaction mixture was stirred at 100° C. overnight under the protectionof N₂ atmosphere. The mixture was concentrated to dryness. H₂O was addedto the residue, the mixture was extracted with EtOAc (20 mL×3), washedwith brine, dried over Na₂SO₄, filtered and concentrated. The residuewas purified by preparative TLC to obtain the target compound (20 mg,45.9%). MS: M/e 719 (M+1)⁺.

Step D:2-(((S)-pent-2-yl)oxy)-7-(piperidin-2-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine

H₂O (2 mL) was added to a mixture of the product of step C (20 mg, 0.027mmol) in TFA (8 mL), and the resulting mixture was stirred at roomtemperature for 2 d. The mixture was concentrated to dryness. Theresidue was purified by preparative HPLC to obtain the target compound(1 mg, 11.2%). ¹H NMR (400 MHz, CD₃OD) δ 7.45 (s, 1H), 5.34 (s, 1H),5.15 (s, 1H), 3.23 (d, J=5.6 Hz, 2H), 2.18 (d, J=6.6 Hz, 1H), 2.02 (s,2H), 1.88 (d, J=13.6 Hz, 2H), 1.57 (d, J=12.1 Hz, 4H), 1.37-1.26 (M,3H), 0.96 (t, J=6.6 Hz, 3H), 0.90 (s, 3H) ppm. MS: M/e 319 (M+1)⁺.

Compound B52 and compound B53:(S)-7-((3,3-dimethylpiperidin-4-ylidene)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amineand7-((3,3-dimethylpiperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazol[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl 4-(hydroxymethyl)-3,3-dimethylpiperidin-1-carboxylate

Under N₂, 9-BBN (26 mL, 13.0 mmol) was added to a solution of tert-butyl3,3-dimethyl-4-methylenepiperidin-1-carboxylate (2 g, 8.88 mmol) in THF(20 mL). After the mixture was stirred at 70° C. for 8 h, the reactionwas cooled to 0° C. and NaOH (3 N, 15 mL) and H₂O₂ (15 mL) were added.The reaction mixture was stirred at 25° C. for 12 h. After completion ofthe reaction, the reaction mixture was quenched with ice water (50 mL)and extracted with DCM (3×80 mL). The combined organic layers were driedover Na₂SO₄ and concentrated under vacuum to obtain a residue. Theresidue was purified by column chromatography on silica gel eluted withethyl acetate (80%) in petroleum ether to obtain the title compound (1.7g, 79%). ¹H NMR (400 MHz, DMSO-d₆) δ 4.37 (t, J=5.2 Hz, 1H), 3.96 (s,1H), 3.64-3.37 (m, 2H), 3.06 (d, J=5.6 Hz, 1H), 2.79-2.54 (m, 2H), 1.67(d, J=13.2 Hz, 1H), 1.38 (s, 9H), 1.32-1.07 (m, 2H), 0.90 (s, 3H), 0.70(s, 3H) ppm.

Step B: Tert-butyl 4-formyl-3,3-dimethylpiperidin-1-carboxylate

DMP (3.6 g, 8.49 mmol) was added to a solution of tert-butyl4-(hydroxymethyl)-3,3-dimethylpiperidin-1-carboxylate (1.7 g, 6.99 mmol)in DCM (30 mL) at 0° C. under N₂. The reaction was stirred at 25° C. for3 h. After completion of the reaction, the reaction mixture was quenchedwith an aqueous Na₂S₂O₃ solution (50 mL) and extracted with DCM (3×50mL). The combined organic layers were washed with an aqueous NaHCO₃solution (50 mL) and brine (2×30 mL), dried over Na₂SO₄ and concentratedunder vacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (40%) inpetroleum ether to obtain the title compound (840 mg, 50%). ¹H NMR (400MHz, DMSO-d6) δ 9.76 (s, 1H), 4.02 (s, 1H), 3.61-3.39 (m, 1H), 2.85-2.57(m, 2H), 2.31 (t, J=7.6 Hz, 1H), 1.59-1.49 (m, 2H), 1.39 (s, 9H), 1.11(s, 3H), 0.83 (s, 3H) ppm.

Step C: Tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-3,3-dimethylpiperidin-1-carboxylate

At −78° C. under N₂, to a solution of(S)—N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(500 mg, 0.959 mmol) in THF (10 mL), n-BuLi (0.9 mL, 1.44 mmol) wasadded. After the mixture was stirred at −78° C. for 0.5 h, tert-butyl4-formyl-3,3-dimethylpiperidin-1-carboxylate (340 mg, 1.41 mmol) in THF(4 mL) was added. The reaction mixture was stirred at −78° C. for 2.5 h.After completion of the reaction, the reaction mixture was quenched withan aqueous NH₄Cl solution (50 mL) and extracted with DCM (3×50 mL). Thecombined organic layers were dried over Na₂SO₄ and concentrated undervacuum to obtain a residue. The residue was purified by columnchromatography on silica gel eluted with ethyl acetate (40%) inpetroleum ether to obtain the title compound (600 mg, 82%). MS: M/e 763(M+1)⁺.

Step D:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(3,3-dimethylpiperidin-4-yl)methanol

Under N₂, tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-3,3-dimethylpiperidin-1-carboxylate(600 mg, 0.786 mmol) was dissolved in TFA (9 mL) and H₂O (1 mL). Thereaction mixture was stirred at 40° C. for 12 h. After completion of thereaction, the solvent was removed under vacuum. The residue was dilutedwith water (20 mL) and DCM (20 mL), and the aqueous phase was acidifiedwith 1 N HCl to adjust pH=1-2. The aqueous phase was washed with DCM(3×30 mL), alkalized with 2 N NaOH to adjust PH=13-14, and extractedwith DCM/i-PrOH (5/1, 3×120 mL). The combined organic layers were driedover Na₂SO₄ and concentrated under vacuum to obtain the crude compound(240 mg, crude). MS: M/e 363 (M+1)⁺.

Step E:(S)-7-((3,3-dimethylpiperidin-4-methylene)methyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazine4-amine and7-(3,3-dimethylpiperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Under N₂,(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(3,3-dimethylpiperidin-4-yl)methanol(240 mg, crude) was dissolved in TFA (5 mL) and Et₃SiH (5 mL). Thereaction mixture was stirred at 90° C. for 12 h. After completion of thereaction, the solvent was removed under vacuum. The residue was dilutedwith water (20 mL) and DCM (20 mL), and the aqueous phase was acidifiedwith 1N HCl to adjust pH=1-2. The aqueous phase was washed with DCM(3×20 mL), alkalized with 2 N NaOH to adjust PH=13-14, and extractedwith DCM/i-PrOH (5/1, 3×120 mL). The combined organic layers were driedover Na₂SO₄ and concentrated under vacuum to obtain a residue. Theresidue was purified by preparative TLC (DCM/MeOH (NH₃)=40/1 to 20/1) toobtain the product compound B52 (3 mg) and compound B53 (25 mg, 9% fortwo steps).

Compound B52: ¹H NMR (400 MHz, CD₃OD) δ 7.55 (s, 1H), 6.62 (s, 1H),5.17-5.05 (m, 1H), 3.16 (t, J=5.6 Hz, 2H), 3.02 (s, 2H), 2.88 (t, J=5.6Hz, 2H), 1.84-1.66 (m, 1H), 1.67-1.52 (m, 1H), 1.53-1.39 (m, 2H), 1.36(s, 9H), 0.97 (t, J=7.2 Hz, 3H) ppm. MS: M/e 345 (M+1)⁺.

Compound B53: ¹H NMR (400 MHz, CD₃OD) δ 7.35 (s, 1H), 5.16-5.01 (m, 1H),3.29-3.15 (m, 2H), 3.13-3.04 (m, 1H), 2.89-2.74 (m, 2H), 2.64-2.51 (m,1H), 1.99-1.85 (m, 1H), 1.82-1.69 (m, 1H), 1.69-1.56 (m, 3H), 1.55-1.41(m, 2H), 1.37 (d, J=6.0 Hz, 3H), 1.22 (s, 3H), 1.14 (s, 3H), 1.02-0.91(m, 3H). MS: M/e 347 (M+1)⁺.

Compound B54:7-((1-(2-(methylamino)propyl)piperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl(1-(methoxy(methyl)amino)-1-oxoprop-2-yl)(methyl)carbamate

HATU (2 g, 5.26 mmol) and DIEA (1.7 mL, 9.62 mmol) were added to asolution of N-(tert-butoxycarbonyl)-N-methylalanine (1 g, 4.93 mmol) inDMF (10 mL) under N₂. After the mixture was stirred for 10 min. thereaction was cooled to 0° C., and N,O-dimethylhydroxylaminehydrochloride (526 mg, 5.42 mmol) was added. The reaction mixture wasstirred at 25° C. for 12 h. After completion of the reaction, thereaction mixture was quenched with ice water (30 mL) and extracted withDCM (3×60 mL). The combined organic layers were washed with brine (3×20mL), dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by column chromatography on silica geleluted with ethyl acetate (30%) in petroleum ether to obtain the titlecompound (1.1 g, 91%). ¹H NMR (400 MHz, DMSO-d₆) δ 5.05-4.67 (m, 1H),3.67 (s, 3H), 3.10 (s, 3H), 2.74 (s, 3H), 1.39 (d, 0.1=7.6 Hz; 9H), 1.21(dd, J=11.6, 7.2 Hz, 3H) ppm.

Step B: Tert-butyl (1-oxoprop-2-yl)carbamate

At 0° C. under N₂. LAH (620 mg, 16.32 mmol) was added to a solution oftert-butyl (1-(methoxy(methyl)amino)-1-oxoprop-2-yl)(methyl)carbamate (1g, 4.07 mmol) in THF (20 mL). After the mixture was stirred for 0.5 h at0° C., the reaction was further stirred for 2 h at 25° C. Aftercompletion of the reaction, the reaction mixture was quenched with 0° C.water (0.7 mL), 15% NaOH (0.7 mL) and water (2.1 mL), and Na₂SO₄ wasadded. The mixture was filtered, the filtrates were combined andconcentrated under vacuum to obtain a residue. The residue was purifiedby column chromatography on silica gel eluted with ethyl acetate (30%)in petroleum ether to obtain the title compound (580 mg, 76%). ¹H NMR(400 MHz, DMSO-d₆) δ 9.53-9.38 (m, 1H), 4.05-3.85 (m, 1H), 2.85 (s, 3H),1.37 (s, 9H), 1.20 (t, J=7.6 Hz, 3H) ppm.

Step C: Tert-butyl(1-(4-((4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)prop-2-yl)(methyl)carbamate

At 0° C. under N₂, to a solution of(S)-2-(pent-2-yloxy)-7-(piperidin-4-ylmethyl)imidazo[2,1-f][1,2,4]triazin-4-amine(50 mg, 0.157 mmol) and tert-butyl (1-oxoprop-2-yl)carbamate (44 mg,0.235 mmol) in MeOH (3 mL), NaBH₃CN (22 mg, 0.349 mmol) was added. Thereaction mixture was stirred at 25° C. for 24 h. After completion of thereaction, the solvent was concentrated under vacuum to obtain a residue.The residue was purified by preparative TLC (DCM/MeOH (NH₃)=18/1) toobtain the title compound (30 mg, 39%). MS: M/e 490 (M+1)⁺.

Step D:7-((1-(2-(methylamino)propyl)piperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

At 0° C. under N₂, to a solution of tert-butyl(1-(4-((4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)methyl)piperidin-1-yl)prop-2-yl)(methyl)carbamate(30 mg, 0.061 mmol) in DCM (3 mL), TFA (2 mL) was added. The reactionmixture was stirred at 25° C. for 1 h. After completion of the reaction,the solvent was concentrated under vacuum to obtain a residue. Theresidue was diluted with DCM/MeOH=1/1 and alkalized with 2 N NaOH. Theresidue was purified by preparative TLC (DCM/MeOH (NH₃)=18/1) to obtainthe title compound (15 mg, 63%). ¹H NMR (400 MHz, CD₃OD) δ 7.30 (s, 1H),5.14-5.05 (m, 1H), 3.36 (s, 1H), 3.04 (s, 1H), 2.84 (d, J=6.8 Hz, 3H),2.69 (s, 3H), 2.50 (s, 2H), 2.29 (s, 1H), 2.05 (s, 1H), 1.91-1.65 (m,4H), 1.64-1.53 (m, 1H), 1.50-1.39 (m, 4H), 1.36 (d, J=6.0 Hz, 3H), 1.25(d, J=6.4 Hz, 3H), 0.97 (t, J=7.2 Hz, 3H) ppm. MS: M/e 390 (M+1)⁺.

Compound B55 and compound B56:7-((8-azabicyclo[3.2.1]oct-3-ylene)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amineand7-((8-azabicyclo[3.2.1]oct-3-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl3-(hydroxymethyl)-8-azabicyclo[3.2.1]octan-8-carboxylate

BH₃-THF (1 M, 2.5 mmol, 5 mL) was added to a solution of tert-butyl3-methylene-8-azabicyclo[3.2.1]octan-8-carboxylate (448 mg, 2 mmol) inTHF (5 mL) at 0° C. under the protection of N2 atmosphere. The reactionwas stirred at room temperature overnight. Then, an aqueous NaOHsolution (3 M, 3.3 mL) and H₂O₂ (30%, 3.3 mL) were added to the mixture,and the reaction was continuously stirred overnight. H₂O was added tothe mixture and the resulting mixture was extracted with ethyl acetate.The combined organic extracts were dried over sodium sulfate, filteredand evaporated, and purified by preparative TLC to obtain the titleproduct (348 mg) as an oil. MS: M/e 242 (M+1)⁺.

Step B: Tert-butyl 3-formyl-8-azabicyclo[3.2.1]octan-8-carboxylate

To a solution of tert-butyl3-(hydroxymethyl)-8-azabicyclo[3.2.1]octan-8-carboxylate (348 mg, 1.54mmol) in DCM (10 mL), Dess-Martin periodinane (979 mg, 2.31 mmol) wasadded. The reaction was stirred at room temperature for 4 h. H₂O wasadded to the mixture and the resulting mixture was extracted with ethylacetate. The combined organic extracts were dried over sodium sulfate,filtered and evaporated, and purified by preparative TLC to obtain thetitle product (200 mg, 57.7%). MS: We 240 (M+1)⁺.

Step C: Tert-butyl3-((4-(bis(4-methoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-8-azabicyclo[3.2.1]octan-8-carboxylate

To a solution of(S)—N,N-bis(4-methoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(290 mg, 0.6 mmol) in THF (4 mL), a solution of n-BuLi (1.6 M, 0.56 mL,0.9 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl3-formyl-8-azabicyclo[3.2.1]octan-8-carboxylate (200 mg, 0.89 mmol) inTHF (2 mL) was added dropwise. The resulting mixture was stirred at −70°C. for 2 h, and then warmed to room temperature to react overnight. Thereaction was quenched with a saturated NH₄Cl solution, extracted withEtOAc (20 mL×3), washed with brine, dried over Na₂SO₄, filtered andconcentrated. The residue was purified by preparative TLC to obtain thetarget compound (60 mg, crude, yellow oil). MS: M/e 701 (M+1)⁺.

Step D:7-((8-azabicyclo[3.2.1]oct-3-ylene)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amineand7-((8-azabicyclo[3.2.1]oct-3-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step C (60 mg,crude) in TFA (4 mL), and the resulting mixture was stirred at 85° C.for 4 h. The mixture was cooled to room temperature and concentrated todryness. TFA (5 mL) was added to the residue, and the reaction washeated at 80° C. overnight. The mixture was concentrated under vacuum.The residue was purified by preparative HPLC to obtain compound B55 (0.6mg) and compound B56 (0.9 mg).

Compound B55: ¹H NMR (400 MHz, CD₃OD) δ 7.46 (s, 1H), 6.60 (s, 1H), 4.53(s, 1H), 4.06 (s, 2H), 2.87 (t, J=14.7 Hz; 2H), 2.52 (d, J=14.5 Hz; 1H),2.09 (s, 1H), 1.96 (d, J=19.5 Hz, 2H), 1.67 (s, 2H), 1.51 (s, 2H), 1.37(s, 2H), 1.26 (d, J=6 Hz, 3H), 0.87 (s, 3H) ppm. MS: M/e 343 (M+1)⁺.

Compound B56: ¹H NMR (400 MHz, CD₃OD) δ 7.30 (s, 1H), 4.53 (s, 1H), 3.91(s, 2H), 3.07 (d, J=8.6 Hz, 2H), 2.29 (d, J=16.2 Hz, 2H), 2.09 (s, 4H),1.94 (s, 1H), 1.69 (d, J=15.5 Hz, 2H), 1.51 (s, 2H), 1.36 (s, 2H), 1.27(d, J=6 Hz, 3H), 0.87 (t, J=7.3 Hz, 3H) ppm. MS: W/e 345 (M+1)⁺.

Compound B57:7-((3,3-difluorpiperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Tert-butyl 3,3-difluoro-4-(hydroxymethyl)piperidin-1-carboxylate

BH₃-THF (1 M, 2.5 mmol, 1.5 mL) was added to a solution of tert-butyl3,3-difluoro-4-methylenepiperidin-1-carboxylate (223 mg, 1 mmol) in THF(5 mL) at 0° C. under the protection of N₂ atmosphere. The reaction wasstirred at room temperature overnight. Then, an aqueous NaOH solution (3M, 1.7 mL) and H₂O₂ (30%, 1.7 mL) were added to the mixture, and thereaction was continuously stirred overnight. H₂O was added to themixture and the resulting mixture was extracted with ethyl acetate. Thecombined organic extracts were dried over sodium sulfate, filtered andevaporated, and purified by preparative TLC to obtain the title product(100 mg) as an oil. MS: M/e 252 (M+1)⁺.

Step B: Tert-butyl 3,3-difluoro-4-formylpiperidin-1-carboxylate

To a solution of tert-butyl3,3-difluoro-4-(hydroxymethyl)piperidin-1-carboxylate (100 mg, 0.41mmol) in DCM (10 mL), Dess-Martin periodinane (265 mg, 0.2 mmol) wasadded. The reaction was stirred at room temperature for 4 h. H₂O wasadded to the mixture and the resulting mixture was extracted with ethylacetate. The combined organic extracts were dried over sodium sulfate,filtered and evaporated, and purified by preparative TLC to obtain thetitle product (48 mg, 48%). MS: M/e 250 (M+1)⁺.

Step C: Tert-butyl4-((4-(bis(4-methoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-3,3-difluorpiperidin-1-carboxylate

To a solution of(S)—N,N-bis(4-methoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(97 mg, 0.2 mmol) in THF (4 mL), a solution of n-BuLi (1.6 M, 0.2 mL,0.3 mmol) was added dropwise at a temperature of −75° C. to −65° C. Onehour later, a suspension of tert-butyl3,3-difluoro-4-formylpiperidin-1-carboxylate (48 mg, 0.2 mmol) in THF (2mL) was added dropwise. The resulting mixture was stirred at −70° C. for2 h, and then warmed to room temperature to react overnight. Thereaction was quenched with a saturated NH₄Cl solution, extracted withEtOAc (20 mL×3), washed with brine, dried over Na₂SO₄, filtered andconcentrated. The residue was purified by preparative TLC to obtain thetarget compound (20 mg, 14.1%). MS: Me 711 (M+1)⁺.

Step D:7-((3,3-difluorpiperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Et₃SiH (4 mL) was added to a mixture of the product of step C (20 mg,0.028 mmol) in TFA (4 mL), and the resulting mixture was stirred at 85°C. for 4 h. The mixture was cooled to room temperature and concentratedto dryness. TFA (5 mL) was added to the residue, and the reaction washeated at 80° C. overnight. The mixture was concentrated under vacuum.The residue was purified by preparative HPLC to obtain the product (1.1mg, 11.1%). ¹H NMR (400 MHz, CD₃OD) δ 7.28 (s, 1H), 5.00 (d, J=5.8 Hz,1H), 2.76 (s, 2H), 2.58-2.40 (m, 2H), 2.09 (t, J=7.6 Hz, 1H), 1.94 (s,1H), 1.74 (s, 1H), 1.65 (s, 1H), 1.62-1.55 (m, 1H), 1.51 (s, 2H), 1.37(s, 2H), 1.27 (d, J=6.2 Hz, 3H), 0.87 (t, J=7.3 Hz, 3H) ppm. MS: M/e 355(M+1)⁺.

Compound B58 and B59: 7-((1-((R orS)-2-(methylamino)propyl)piperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amineand 7-((1-((S orR)-2-(methylamino)propyl)piperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[21-f][1,2,4]triazin-4-amine

Compound B547-((1-(2-(methylamino)propyl)piperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine(150 mg, 0.386 mmol) was purified by preparative SFC (chiral PAK AD-Hcolumn, 3 cm*25 cm, 5 um, flow rate 20 mL/min, phase: hexane (2 mMNH₃-MeOH): IPA=90:10. UV: 220 nm, 25° C.), thereby obtaining compoundB58 (55 mg) and compound B59 (53 mg).

Compound B58: ¹H NMR (400 MHz, CD₃OD) δ 7.29 (s, 1H), 5.14-5.02 (m, 1H),2.94 (d, J=11.2 Hz, 1H), 2.85-2.71 (m, 4H), 2.40 (s, 3H), 2.32-2.14 (m,2H), 2.10 (t, J=11.2 Hz, 1H), 1.91-1.70 (m, 3H), 1.70-1.54 (m, 3H),1.54-1.25 (m, 7H), 1.02 (d, J=6.4 Hz, 3H), 0.97 (t, J=7.2 Hz, 3H) ppm.MS: M/e 390 (M+1)⁺.

Compound B59: ¹H NMR (400 MHz, CD₃OD) δ 7.29 (s, 1H), 5.14-5.04 (m, 1H),2.93 (d, J=11.2 Hz, 1H), 2.85-2.64 (m, 4H), 2.40 (s, 3H), 2.30-2.12 (m,2H), 2.08 (t, J=11.6 Hz, 1H), 1.90-1.70 (m, 3H), 1.70-1.53 (m, 3H),1.53-1.25 (m, 7H), 1.02-0.93 (m, 6H) ppm. MS: Me 390 (M+1)⁺.

Compound B60:7-((3-methylpiperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

Step A: Methyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-3-methylpiperidin-1-carboxylate

At −78° C. under N₂, to a solution of(S)-7-bromo-N,N-bis(2,4-dimethoxybenzyl)-2-(pent-2-yloxy)imidazo[2,1-f][1,2,4]triazin-4-amine(500 mg, 0.833 mmol) in THF (10 mL), n-BuLi (1.04 mL, 1.664 mmol) wasadded. After the mixture was stirred at −78° C. for 0.5 h, tert-butyl4-formyl-3-methylpiperidin-1-carboxylate (284 mg, 1.251 mmol) was added.The reaction mixture was stirred at −78° C. for 2.5 h. After completionof the reaction, the reaction mixture was quenched with an aqueous NH₄Clsolution (20 mL) and extracted with DCM (3×30 mL). The combined organiclayers were dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by column chromatography on silica geleluted with ethyl acetate (40%) in petroleum ether to obtain the titlecompound (400 mg, 64%). MS: M/e 749 (M+1)⁺.

Step B:(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(3-methylpiperidin-4-yl)methanol

Under N₂, tert-butyl4-((4-(bis(2,4-dimethoxybenzyl)amino)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(hydroxy)methyl)-3-methylpiperidin-1-carboxylate(400 mg, 0.534 mmol) was dissolved in TFA (9 mL) and H₂O (1 mL). Thereaction mixture was stirred at 40° C. for 12 h. After completion of thereaction, the solvent was removed under vacuum. The residue was dilutedwith water (20 mL) and DCM (20 mL), and the aqueous phase was acidifiedwith 1 N HCl to adjust pH=1-2. The aqueous phase was washed with DCM (3′20 mL), alkalized with 2 N NaOH to adjust PH=13-14, and extracted withDCM/i-PrOH (5/1, 3×60 mL). The combined organic layers were dried overNa₂SO₄ and concentrated under vacuum to obtain the crude compound (180mg, crude). MS: M/e 349 (M+1)⁺.

Step C:7-((3-methylpiperidin-4-yl)methyl)-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-4-amine

(4-amino-2-(((S)-pent-2-yl)oxy)imidazo[2,1-f][1,2,4]triazin-7-yl)(3-methylpiperidin-4-yl)methanol(180 mg, crude) was dissolved in TFA (5 mL) and Et₃SiH (5 mL) under N₂.The reaction mixture was stirred at 90° C. for 12 h. After completion ofthe reaction, the solvent was removed under vacuum. The residue wasdiluted with water (20 mL) and DCM (20 mL), and the aqueous phase wasacidified with 1 N HCl to adjust pH=1-2. The aqueous phase was washedwith DCM (3×20 mL), alkalized with 2 N NaOH to adjust PH=13-14, andextracted with DCM/i-PrOH (5/1, 3×120 mL). The combined organic layerswere dried over Na₂SO₄ and concentrated under vacuum to obtain aresidue. The residue was purified by preparative HPLC to obtain thetitle compound (12 mg). ¹H NMR (400 MHz, CD₃OD) δ 7.58 (s, 1H), 5.13 (d,J=6.0 Hz, 1H), 3.34 (s, 1H), 3.15 (dd, J=10.4, 4.4 Hz, 2H), 3.07-2.86(m, 3H), 2.36 (s, 1H), 2.15 (s, 1H), 1.84-1.68 (s, 3H), 1.67-1.55 (m,1H), 1.55-1.40 (m, 2H), 1.37 (d, J=6.4 Hz, 3H), 1.16 (d, J=7.2 Hz, 3H),0.97 (t, J=7.2 Hz, 3H) ppm. MS: M/e 333 (M+1)⁺.

TLR8 Stimulation Determined by HEK-Blue Detection

This assay was designed to study the stimulation of human TLR 8 proteinin HEK-blue hTLR 8 tool cell line by monitoring the activation of NF-κB.HEK-blue hTLR8 cells were obtained by co-transfection of hTLR8 gene andoptimized secretory embryonic alkaline phosphatase (SEAP) reporter geneinto HEK293 cells. SEAP reporter gene was put under the control ofIFN-pi minimal promoter fused with five NF-κB and AP-1-binding sites.NF-κB and AP-1 were activated by stimulation with TLR 8 ligand, thusinducing the expression of SEAP. The level of SEAP can be easilydetermined by HEK-Blue Detection (a cell culture medium that allowsreal-time detection of SEAP). HEK-Blue Detection comprises all nutrientsneeded for cell growth and specific SEAP color substrates. Thehydrolysis of substrate by SEAP produces purple/blue color which can bemeasured by spectrophotometer.

When growing to 50-80% confluence, HEK-Blue hTLR7/8 cells were platedinto 96-well plates (costar 3599) at a density of 40.000 cells/well.Then, the compound serially diluted at 10 points with a finalconcentration ranging from 1 nM to 10 um in 0.1% DMSO/HEK-Blue Detectionwas added. The plates were then incubated in 5% CO₂ at 37° C. for 16 h.Optical density at 620-655 nm was read on BMG PHERAstar FSX instrument.The EC50 of each compound was determined by calculating the maximumactivation percentage identified using Resiquimod or motolimod.

The EC50 of the tested compound of the present invention is as follows.

TABLE 1 Compounds for HEK-Blue hTLR8 cells (″D″ denotes EC50 >10 μmol)Compound EC50 Compound EC50 No. Structure (nmol) No. Structure (nmol) B1

51 B2

15 B3

346 B4

347 B5

917 B6

8.2 B7

1288 B8

515 B9

529 B10

172 B11

1794 B12

19 B13

387 B14

138 B15

1076 B16

8493 B17

3953 B18

2719 B19

66 B20

558 B21

D B22

D B23

143 B24

D B25

63 B26

99 B27

20 B28

308 B29

D B30

26 B31

103 B32

22 B33

766 B34

225 B35

921 B36

D B37

D B38

47 B39

127 B40

1006 B41

D B42

36 B43

24 B44

D B45

531 B46

D B47

84 B48

14.7 B49

7.5 B50

209 B51

410 B52

>10 μM B53

3863 B54

22 B55

>10 μM B56

1925 B57

>10 μM B58

24 B59

21 B60

917

Determination of PBMC (Peripheral Blood Monocyte)

Cell Preparation, Separation and Culture

Human whole blood was collected from healthy volunteers using BDVacutainer® Lithium Heparin Tubes. PBMCs were prepared using Ficollseparation medium (GE Healthcare) by SepMate™ (STEMCELL). The cellsurvival rate was over 85% as monitored by Countstar. PBMCs werecultured in RPMI 1640 (Gibco) 101% (v/v) FBS (Gibco), 1×MEM NEAA(Gibco), 1× GlutaMAX (Gibco), 1 mM sodium pyruvate (Gibco), 50 uM2-mercaptoethanol (sigma), and 100 U/mi penicillin-streptomycin (Thermofisher Scientific).

Cell Stimulation

PBMCs were plated into 96-well plates (costar 3894) with a density of2N10{circumflex over ( )}5 cells/well. Then. TLR7/8 compound was added,and serial dilution was carried out at ten points. The finalconcentration in 0.1% DMSO/RPMI 1640 ranged from 1 nM to 10 μM. Then,the plates were incubated in 5% CO₂ at 37° C. for 24 h.

HTRF (Homogeneous Time-Resolved Fluorescence)

After the specified time point, according to the manufacturersrecommendations, the cytokines in the cell culture supernatant weremeasured by Human IL6 kit (cisbio) and Human TNF alpha kit (cisbio). TheEC50 of each compound was determined by calculating the maximumactivation percentage identified using Resiquimod or Motolimod.

TABLE 2 PBMC determination of compounds (“D” denotes EC 50 > 10 μmol)Compound TNF- Compound No. IL6 alpha No. IL6 TNF-alpha B6  162 115 B7  DD B12  14  10 B19 247 430 B25 236 456 B27 228 326 B30  85 153 B38  28 39

Although the present invention has been described in connection with thespecific embodiments set forth above, many alternatives, modificationsand other variations thereof will be obvious to those skilled in theart. All such alternatives, modifications and variations are intended tofall within the spirit and scope of the present invention.

1. A compound of formula (I),

or a pharmaceutically acceptable salt thereof, or a stereoisomerthereof, wherein: X is N or CR⁷; wherein R⁷ is hydrogen, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl; L¹ is —(CR^(a)R^(b))_(m)—, —O—, —S—, —S(O)—, —SO₂—, —C(O)—,—C(O)O—, —OC(O)—, —NR^(a)—, —C(O)NR^(a)—, —NR^(a)C(O)—, —NR^(a)C(O)O—,—NR^(a)C(O)NR^(b)—, —SO₂NR^(a)—, —NR^(a)SO₂—, —NR^(a)S(O)₂NR^(b)—,—NR^(a)S(O)NR^(b)—, —C(O)NR^(a)SO₂—, —C(O)NR^(a)SO—, or—C(═NR^(a))NR^(b)—, wherein m is 0 to 8, and one or two CR^(a)R^(b)moieties in —(CR^(a)R^(b))_(m)— are not replaced or replaced by one ormore moieties selected from O, S, SO, SO₂, C(O) and NR^(a); R^(a) andR^(b) in each occurrence are independently hydrogen, halogen, alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl, heteroaryl or —OR^(c); wherein R^(c) is hydrogen, alkyl,alkoxy-alkyl-, alkenyl, alkynyl, cycloalkyl, aryl, heterocyclyl orheteroaryl; R¹ is —OR^(1a), —SR^(1a), —NR^(1a)R^(1b), —COR^(1a),—SO₂R^(1a), —C(═O)OR^(1a), —C(═O)NR^(1a)R^(1b),—C(═NR^(1a))NR^(1b)R^(1c), —N(R^(1a))C(═O)R^(1b),—N(R^(1a))C(═O)OR^(1b), —N(R^(1a))C(O)NR^(1b)R^(1c),—N(R^(1a))S(O)NR^(1b)R^(1c), —N(R^(1a))S(O)₂NR^(1b)R^(1c),—NR^(1a)SO₂R^(1b), alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl, or heteroaryl, wherein the alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl are each independently and optionally substitutedwith one or two or three substituents R^(1d); R^(1a), R^(1b) and R^(1c)are independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl, whereinthe alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl or heteroaryl are each optionally substituted withone or two or three substituents selected from: halogen, —C₁₋₈ alkyloptionally substituted with R^(1e), cycloalkyl optionally substitutedwith R^(1e), heterocyclyl optionally substituted with R^(1e), aryloptionally substituted with R^(1e), heteroaryl optionally substitutedwith R^(1e), CH₃—(OCH₂CH₂)_(n)— (where n is 3 to 10) or —OR^(1f);wherein R^(1e) is halogen, nitro, cyano, hydroxyl, amino (—NH₂),alkylamino, dialkylamino, —C₁₋₆ alkyl optionally substituted withhalogen, carboxyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl,and dialkylaminocarbonyl; wherein R^(1f) is alkyl, cycloalkyl,heterocyclyl, aryl or heteroaryl, each being optionally substituted with—C₁₋₄ alkyl or halogen; R^(1d) in each occurrence is independentlyhydrogen, oxo, —CN, —NO₂, hydroxyl, amino (—NH₂), alkylamino,dialkylamino, halogen, haloalkyl, alkyl, haloalkoxy, alkoxy, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl; R² and R³ in each occurrence are independently hydrogen,alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl or heteroaryl, wherein the alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroarylis optionally substituted with 1-3 substituents selected from: oxo, —CN,—NO₂, amino (—NH₂), alkylamino, dialkylamino, halogen, hydroxyl,haloalkyl, alkyl, haloalkoxy, alkoxy, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl; R⁴ ishydrogen, halogen, cyano, —NO₂, —OR^(4a), —SR^(4a), —NR^(4a)R^(4b),—COR^(4a), —SO₂R^(4a), —C(═O)OR^(4a), —C(═O)NR^(4a)R^(4b),—C(═NR^(4a))NR^(4b)R^(4c), —N(R^(4a))C(═O)R^(4b),—N(R^(4a))C(═O)OR^(4b), —N(R^(4a))C(O)NR^(4b)R^(4c),—N(R^(4a))S(O)NR^(4b)R^(4c), —N(R^(4a))S(O)₂NR^(4b)R^(4c),—NR^(4a)SO₂R^(4b), alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl, or heteroaryl, wherein the alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl are each independently and optionally substitutedwith one or two or three substituents R^(4d); R^(4a), R^(4b) and R^(4c)are independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl, whereinthe alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl or heteroaryl are each optionally substituted withhalogen, hydroxyl, NH₂—, alkylamino, dialkylamino or alkoxy; R^(4d) ineach occurrence is independently hydrogen, oxo, —CN, —NO₂, halogen,hydroxyl, NH₂—, alkylamino, dialkylamino, alkyl, alkoxy, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl, wherein the alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachoptionally substituted with halogen, hydroxyl, NH₂—, alkylamino,dialkylamino or alkoxy; ring A is a cycloalkyl or heterocyclyl ring; R⁵is halogen, oxo, hydroxyl, alkyl, haloalkyl, alkoxy, haloalkoxy or—C(═O)OR^(5a), wherein R^(5a) is hydrogen, alkyl or haloalkyl; p is 0,1, 2 or 3; L² is a direct bond, —(CR^(f)R^(g))_(t)—, —O—, —S—, —S(O)—,—SO₂—, —C(O)—, —C(O)O—, —OC(O)—, or —NR^(d)— where R^(d) is —C₁₋₆ alkyl,wherein t is 1 to 8, and one or two CR^(f)R^(g) moieties in—(CR^(f)R_(g))_(t)— are not replaced or replaced by one or more moietiesselected from O, S, SO, SO₂, C(O) and NR^(f); R^(f) and R^(g) areindependently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl; R⁶ ishydrogen, —NR^(6a)R^(6b), alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl, whereinthe alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl or heteroaryl are each independently and optionallysubstituted with one or two or three substituents R^(6c); R^(6a) andR^(6b) are independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl, whereinthe alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl or heteroaryl are each optionally substituted withhalogen, hydroxyl, NH₂—, alkylamino, dialkylamino or alkoxy; R^(6c) isindependently hydrogen, halogen, cyano, —NO₂, —OR^(6d), —SR^(6d),—NR^(6d)R^(6e), —COR^(6d), —SO₂R^(6d), —C(═O)OR^(6d),—C(═O)NR^(6d)R^(6f), —C(═NR^(6d))NR^(6e)R^(6f), —N(R^(6d))C(═O)R^(6e),—N(R^(6d))C(═O)OR^(6e), —N(R^(6d))C(O)NR^(6e)R^(6f),—N(R^(6d))S(O)NR^(6e)R^(6f), —N(R^(6d))S(O)₂NR^(6e)R^(6f),—NR^(6d)SO₂R^(6e), alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl or heteroaryl, wherein the alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl,aryl or heteroaryl are each independently and optionally substitutedwith one or two or three substituents R^(6g), R^(6d), R^(6e) and R^(6f)are independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl, whereinthe alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,heterocyclyl, aryl or heteroaryl are each optionally substituted withone or two or three substituents R^(6g); R^(6g) in each occurrence isindependently hydrogen, halogen, cyano, —NO₂, —OR^(6h), —SR^(6h),—NR^(6h)R^(6i), —COR^(6h), —SO₂R^(6h), —C(═O)OR^(6h),—C(═O)NR^(6h)R^(6i), —C(═NR^(6h))NR^(6i)R^(6j), —N(R^(6h))C(═O)R^(6i),—N(R^(6h))C(═O)OR^(6i), —N(R^(6h))C(O)NR^(6i)R^(6j),—N(R^(6h))S(O)NR^(6i)R^(6j), —N(R^(6h))S(O)₂NR^(6i)R^(6h),—NR^(6h)SO₂R^(6i), alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, heterocyclyl, aryl or heteroaryl; and R^(6h), R^(6i) andR^(6j) are independently hydrogen, alkyl, alkoxy, alkenyl, alkynyl,cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, aryl orheteroaryl, wherein the alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, aryl or heteroaryl are eachindependently and optionally substituted with one or two or threesubstituents selected from: halogen, —C₁₋₄ alkyl, —C₁₋₄ alkoxy,hydroxyl, nitro, —NH₂, alkylamino, dialkylamino or cyano.
 2. Thecompound according to claim 1, wherein X is N.
 3. The compound accordingto claim 1, wherein m is 1 to 5, or 1 to 3, or
 1. 4. The compoundaccording to claim 1, wherein L¹ is —CR^(a)R^(b)—, wherein R^(a) andR^(b) in each occurrence are independently hydrogen, halogen, —C₁₋₈alkyl (preferably —C₁₋₄ alkyl, and more preferably methyl) or —OH; andL¹ is —CH₂—, —CH(OH)— or —CH(CH₃)—.
 5. The compound according to claim1, wherein R¹ is —OR^(1a) or —NR^(1a)R^(1b), wherein R^(1a) and R^(1b)are as defined for formula (I).
 6. The compound according to claim 1,wherein R¹ is —OR^(1a) or —NR^(1a)R^(1b), wherein R^(1a) and R^(1b) areindependently hydrogen, —C₁₋₈ alkyl or —C₂₋₈ alkenyl, wherein the —C₁₋₈alkyl or —C₂₋₈ alkenyl are each optionally substituted with one or twoor three substituents selected from: heterocyclyl optionally substitutedwith R^(1e), aryl optionally substituted with R^(1e), CH₃—(OCH₂CH₂)_(n)—(where n is 3 to 10, preferably 4 to 8, and more preferably 5 to 7) or—OR^(1f); wherein R^(1e) is halogen, —C₁₋₆ alkyl optionally substitutedwith halogen, carboxyl, alkoxycarbonyl, aminocarbonyl,alkylaminocarbonyl, and dialkylaminocarbonyl; wherein R^(1f) is —C₁₋₈alkyl, aryl or heteroaryl, each being optionally substituted with —C₁₋₄alkyl or halogen.
 7. The compound according to claim 1, wherein R¹ is—OR^(1a), wherein R^(1a) is —C₁₋₈ alkyl optionally substituted with oneor two or three substituents selected from: halogen, —C₁₋₈ alkyloptionally substituted with R^(1e), cycloalkyl optionally substitutedwith R^(1e), heterocyclyl optionally substituted with R^(1e), aryloptionally substituted with R^(1e), heteroaryl optionally substitutedwith R^(1e), CH₃—(OCH₂CH₂)_(n)— (where n is 3 to 10) or —OR^(1f),wherein R^(1e) and R^(1f) are as defined for formula (I).
 8. Thecompound according to claim 1, wherein R¹ is —OR^(1a), wherein R^(1a) isbranched alkyl, preferably —C₄₋₈ alkyl, wherein the branched substituentis at the α position relative to the oxygen atom, including but notlimited to but-2-yl, pent-2-yl, pent-3-yl, hept-2-yl, hept-3-yl,hept-4-yl, oct-2-yl, oct-3-yl, oct-4-yl, or oct-5-yl.
 9. The compoundaccording to claim 1, wherein R² and R³ in each occurrence eachindependently hydrogen or C₁₋₈ alkyl, and preferably C₁₋₆ alkyl.
 10. Thecompound according to claim 1, wherein R⁴ is hydrogen.
 11. The compoundaccording to claim 1, wherein R⁵ is halogen, oxo, hydroxyl, C₁₋₈ alkyl,halogenated C₁₋₈ alkyl, C₁₋₈ alkoxy, halogenated C₁₋₈ alkoxy or—C(═O)OR^(5a), wherein R^(5a) is hydrogen, C₁₋₈ alkyl or halogenatedC₁₋₈ alkyl; and p is 0, 1 or
 2. 12. The compound according to claim 1,wherein p is 0 or
 1. 13. The compound according to claim 1, wherein ringA is a heterocyclyl or cycloalkyl ring.
 14. The compound according toclaim 1, wherein ring A is azetidin-3-yl, azepan-4-yl; piperidin-2-yl,piperidin-3-yl, piperidin-4-yl; pyrrolidin-1-yl, pyrrolidin-2-yl,pyrrolidin-3-yl; piperazin-1-yl; 7-azaspiro[3.5]non-2-yl,2-azaspiro[3.3]hept-6-yl, 7-azaspiro[3.5]non-2-yl,2-azaspiro[3.5]non-7-yl; 3-azabicyclo[3.1.0]hex-6-yl,2-azabicyclo[2.2.1]hept-5-yl, 8-azabicyclo[3.2.1]oct-3-yl,2-azabicyclo[4.1.0]hept-5-yl; cyclobutyl, bicyclo[1.1.1]pent-1-yl;bicyclo[1.1.1]pent-1-yl; or 1,2,3,6-tetrahydropyridin-4-yl.
 15. Thecompound according to claim 1, wherein R⁵ and L²-R⁶ are eachindependently methyl, ethyl, isopropyl; 2-(methylamino)ethyl; benzyl;piperidin-4-ylmethyl; (methylamino)methyl; 2-(methylamino)ethyl;hydroxymethyl; trifluoromethyl; pyrrolidin-3-yl, pyrrolidin-2-yl,piperidin-4-yl; hydroxyl; oxo; fluorine; ethoxycarbonyl; phenyl;methylamino or amino.
 16. The compound according to claim 1, wherein themoiety

is piperidin-4-yl, 1-methylpiperidin-4-yl,1-(2-(methylamino)ethyl)piperidin-4-yl,1-(pyrrolidin-3-yl)piperidin-4-yl, 1-(pyrrolidin-2-yl)piperidin-4-yl,1-(piperidin-4-yl)piperidin-4-yl, 4-methylpiperidin-4-yl,3-hydroxypiperidin-4-yl, 3-oxopiperidin-4-yl, 3-fluopiperidin-4-yl,3,3-difluorpiperidin-4-yl, 3-benzylpiperidin-4-yl,1-(piperidin-4-ylmethyl)piperidin-4-yl,4-((methylamino)methyl)piperidin-1-yl, 2-ethylpiperidin-4-yl,2-ethoxycarbonylpiperidin-4-yl, 2-hydroxymethylpiperidin-4-yl,1-methyl-2-((methylamino)methyl)piperidin-4-yl,1-isopropyl-2-((methylamino)methyl)piperidin-4-yl,2,6-dimethylpiperidin-4-yl, 2,2-dimethylpiperidin-4-yl,2-(trifluoromethyl)piperidin-4-yl, 2-phenylpiperidin-4-yl,4-(methylamino)piperidin-1-yl; piperidin-2-yl; pyrrolidin-3-yl;azetidin-3-yl; azepan-4-yl; (R)-3-methylpiperazin-1-yl;(S)-3-methylpiperazin-1-yl; (S)-3-methylpiperazin-1-yl;(R)-3-methylpiperazin-1-yl; 2-hydroxy-7-azaspiro[3.5]non-2-yl;3-azabicyclo[3.1.0]hex-6-yl; 2-azaspiro[3.3]hept-6-yl;7-azaspiro[3.5]non-2-yl; 2-azaspiro[3.5]non-7-yl;2-azabicyclo[2.2.1]hept-5-yl; 8-azabicyclo[3.2.1]oct-3-yl;3-aminocyclobutyl; 1-(2-(methylamino)ethyl)-2-oxo-piperidin-4-yl;2-azabicyclo[4.1.0]hept-5-yl; 1,2,3,6-tetrahydropyridin-4-yl;3-aminobicyclo[1.1.1]pent-1-yl; or3-((methylamino)methyl)bicyclo[1.1.1]pent-1-yl.
 17. A compound, selectedfrom the specific compounds exemplified by the invention or apharmaceutically acceptable salt or a stereoisomer thereof.
 18. Apharmaceutical composition comprising the compound of claim 1 or apharmaceutically acceptable salt thereof, and at least onepharmaceutically acceptable carrier or excipient.
 19. A method forregulating TLR8, comprising administering the compound of claim 1 or apharmaceutically acceptable salt thereof to an individual.
 20. A methodfor treating a disease or disorder in a patient, comprisingadministering to the patient a therapeutically effective amount of thecompound of claim 1 or a pharmaceutically acceptable salt thereof as aTLR8 agonist.
 21. The method according to claim 20, wherein the diseaseor disorder is cancer.